Ebook Mosby''s manual of diagnostic and laboratory tests (5th edition): Part 1

(BQ) Part 1 book Mosby''s manual of diagnostic and laboratory tests presents the following contents: Guidelines for proper test preparation and performance, blood studies.

i

Pagana: Mosby’s Manual of Diagnostic and Laboratory Tests, ed 5,

Case Studies

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Pagana manual

Kathleen Deska Pagana, PhD, RN

Timothy J Pagana, MD, FACS

Medical Director, Emeritus The Kathryn Candor Lundy Breast Health Center and The SurgiCenter

Susquehanna Health System Williamsport, Pennsylvania

3251 Riverport Lane

St Louis, Missouri 63043

MOSBY’S MANUAL OF DIAGNOSTIC AND LABORATORY TESTS, FIFTH EDITION ISBN: 978-0-323-08949-4

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2010, 2006, 2002, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

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This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

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We lovingly dedicate this book to our delightful grandchildren:

Ella Marie Gaul Jocelyn Elizabeth Gaul Timothy William Gaul Justin Aquinas Gaul Juliana Kathleen Pericci Luke Michael Pericci

Michael Andary, MD, MS

Professor

College of Osteopathic Medicine

Michigan State University

East Lansing, Michigan

Valerie Bush, PhD, FACB

Clinical Laboratory Director

Bassett Medical Center

Cooperstown, New York

Karmen A Grant, MS, RN, CNDR

Nursing Instructor

Rogers State University

Claremore, Oklahoma

Joseph Hawkins, MS Ed., CNMT

Associate Professor and Program Director

Nuclear Medicine Technology

Florida Hospital College of Health Sciences

Geralyn López-de-Victoria, PhD, MS

Science Department ChairMidlands Technical CollegeWest Columbia, South Carolina

Carla R Lynch, MS, RN

Nursing InstructorRogers State UniversityClaremore, Oklahoma

Naser Nejadi, BS, MSc

Tehran University of Medical SciencesTehran, Iran

Sandra Rome, RN, MN, AOCN

Clinical Nurse SpecialistCedars-Sinai Medical CenterLos Angeles, California

Bonnie L Welniak, MSN, RN

Assistant Professor of NursingMonroe County Community CollegeMonroe, Michigan

Reviewers

This book provides the user with an up-to-date, extensive manual that allows rapid access to clinically relevant laboratory and diagnostic tests A unique feature of this manual is its consistent format, which provides a comprehensive approach to laboratory and diagnostic tests Tests are categorized according

to either the method of testing (e.g., x-ray, ultrasound, nuclear scan) or the type of specimen (e.g., blood, urine, stool) used for testing Every chapter of this book is based on this categorization Each chapter begins with an alphabetical listing of all tests in the chapter to aid the user in locating discussions quickly An overview follows the list and contains general information concerning test methods and related patient care

Chapter 1 includes a discussion of guidelines for proper test preparation and performance New coding requirements for ordering tests have been added along with a description of common laboratory methods Standard Precautions and other clinically important information for the health care provider are included to ensure accurate diagnostic and laboratory testing This information is essential for health care economics so that tests are performed in a timely fashion and do not need to be repeated because of problems in patient preparation, test procedure, or specimen handling Communication and collaboration with other health care providers are emphasized The privacy rules resulting from the Health Insurance Portability and Accountability Act (HIPAA) are explained in relationship to diagnostic and laboratory test results

Throughout the book, information is explained in a comprehensive manner to enhance full understanding of each particular test Every feature of test discussion is geared to provide complete information in a sequence that best simulates priorities in clinical practice The following information

is provided, whenever possible, for a thorough understanding of each diagnostic test:

• Name of test Tests are listed by their complete name A complete list of abbreviations and alternative

test names follows each main entry

• Normal findings Normal values are listed, when applicable, for the infant, child, adult, and elderly

person Also, where appropriate, values are separated into categories of male and female We realize that normal ranges for laboratory tests vary significantly depending on the method of testing and the particular laboratory For this reason, we strongly encourage the user to check the normal values

at the institution where the test is performed This should be relatively easy because most laboratory reports indicate normal values

• Critical values These values give an indication of results that are well outside the usual range for

normal These results generally require immediate intervention

• Indications This section describes the main uses for each test Emphasis is placed on the type of

pa-tient signs and symptoms that lead to the indications for each test

• Test explanation This section provides a comprehensive description of each test The explanation

includes fundamental information about basic pathophysiology related to the test methods, what diseases the test results may indicate, and the location where the test is generally performed Also, in this section, patient sensation, test duration, and the type of health care professional involved in the testing are described

Preface

viii

• Contraindications This information alerts the user to patients who should not have the test

per-formed As in other segments of the book, each contraindication is fully explained with an in-depth rationale Patients frequently highlighted in this section include those who are pregnant, who are allergic to iodinated or contrast dye, or who have bleeding disorders

• Potential complications This section alerts the user to potential problems that will necessitate astute

posttesting assessments and interventions Not only is each complication fully explained in detail, but also patient symptoms and appropriate interventions are described For example, a potential complication of an intravenous pyelogram is renal failure, especially in the elderly patient An ap-propriate intervention may be to hydrate the patient before the test and force fluids afterward

• Interfering factors This section includes a thorough discussion of factors that can invalidate or alter

the test results An important feature of this section is the inclusion of drugs that can interfere with test results Drugs that increase or decrease test values are indicated by a drug icon ( ) for quick access

• Procedure and patient care This section emphasizes the role of nurses and other health care

provid-ers in diagnostic and laboratory testing by addressing psychosocial and physiologic interventions Patient teaching priorities are noted with a special icon ( ) to highlight information to be com-municated to patients For quick location of essential information concerning the testing procedure, this section is divided into before, during, and after time sequences

• Before This section addresses the need to explain the procedure and to allay patient concerns or

anxieties Dietary restrictions, bowel preparations, baseline pretest assessment, and the need for informed consent are discussed

• During This section provides a complete and thorough description of the testing procedure,

alternative procedures, and methods of testing In most instances, a step-by-step description of testing procedures is provided This information is important because all health care providers involved in the particular test should have a good understanding of what the procedure entails so they can assist more completely in the testing process

• After This section includes vital information that the nurse or other health care provider should

know concerning postprocedure care of the patient This includes information on specific posttest assessment, medication administration, recognition of posttest complications (with suggestions for interventions), home care, and follow-up

• Test results and clinical significance As the name implies, this section describes the significance of

the test findings A unique feature of this manual, compared with other books on diagnostic and laboratory tests, is an extensive discussion of the pathophysiology of the disease process and how

it relates to the test result This provides enhanced understanding of the diagnostic test and better understanding of many disease processes

• Related tests This section, another unique feature of the text, includes a list of tests that are related to

the main test under discussion This includes tests that provide similar information, tests that vide confirmatory information, and other tests used to evaluate the same organ, disease process, or symptom complex A short description and page numbers for all related tests are included for ease in cross-referencing This aids the reader to develop a broader understanding of diagnostic testing and indicates where the reader may go to obtain more information on the topic of interest

pro-This logical format emphasizes clinically relevant information The clarity of the format facilitates a full understanding of content essential to both students and health care providers, and its uniformity allows the user to quickly recognize where information of interest may be found

Multiple colors have been used to help locate tests, highlight critical information, and generally improve the readability of the text Another key feature is the use of color photographs and illustrations throughout the book Many tables are also included to simplify or summarize complex material regarding clinical care, test categories, or disease processes

Preface ix

Feature boxes are used throughout the book to highlight and summarize important clinical data

They allow the reader to assimilate important information at a glance There are three types of feature

boxes: Clinical Priorities, Age-Related Concerns, and Home Care Responsibilities Clinical Priorities

boxes emphasize pertinent information specific to understanding and performing a particular test For example, coagulation studies must be assessed before invasive studies (e.g., liver biopsy) that may cause bleeding Chest x-ray examinations should be performed after procedures (e.g., pleural biopsy)

that may cause a pneumothorax Age-Related Concerns boxes primarily address pediatric and geriatric

priorities For example, the risk for dye-induced renal failure is emphasized in the dehydrated elderly patient scheduled for an intravenous pyelogram The bowel preparation for children of different ages is

described in the barium enema study Home Care Responsibilities boxes focus on factors that need to be

addressed after a test is performed With an increasing number of procedures being performed on an outpatient basis, the patient has the responsibility for detecting problems and knowing what to do when they occur Often, the patient returns home with instructions or guidelines for recognizing problems such as infection, bleeding, or urinary retention

New to this edition is a comprehensive listing of diagnostic and laboratory tests used when evaluating

a patient with a common disease or condition These are based on the International Classification of Disease (ICD) codes (see p xi) This alphabetical list should be invaluable to readers who want to know the testing possibilities for common problems such as adrenal abnormalities, AIDS, Alzheimer’s disease, bowel obstruction, breast cancer, and others For emphasis, this material is placed before Chapter 1.Also new is a description of commonly performed laboratory methods, which is placed in Chapter 1 This section explains methods used to evaluate blood, urine, spinal fluid, and other specimens Methods such as latex agglutination, agglutination inhibition, hemagglutination, electrophoresis, immunoassay, polymerase chain reaction, and FISH techniques are examples

Appendix A, Alphabetical List of Tests, helps the user locate specific tests at a glance Appendix B, List

of Tests by Body System, familiarizes the user with other related studies the patient or client may need

or the user may want to review This information should be especially useful for students and health care providers working in specialized areas For example, all tests related to infertility are listed in the

Reproductive System section Appendix C provides a list of Panel Tests such as cardiac enzymes, lipid profile, liver profile, and thyroid studies Appendix D contains a list of Abbreviations for Diagnostic and Laboratory Tests Finally, a comprehensive Index includes the names of all tests and their synonyms

and other relevant terms found within the tests Typical Abbreviations and Units of Measurement are located on the inside cover

Many new studies such as anti-glycan antibodies, laboratory genetics, neuron-specific enolase, galectin-3, and ProstaScint scan have been added All other studies have been revised and updated Outdated tests have been eliminated Illustrations and photographs have been extensively updated, and many new ones have been added

We sincerely thank Mosby/Elsevier for invaluable assistance and dedication to our books over

30 years We also thank our editors—Jean Sims Fornango, Brandi Flagg, and Jodi Willard—for their enthusiasm and support We invite comments from users of this book so that we may improve our goal

of providing useful and relevant diagnostic and laboratory test information to users of future editions

Kathleen D Pagana Timothy J Pagana

Testing for Common Diseases and Conditions, xi

1 Guidelines for Proper Test Preparation and Performance, 1

A Alphabetical List of Tests, 1136

B List of Tests by Body System, 1145

C Panel Testing, 1152

D Abbreviations for Diagnostic and Laboratory Tests, 1154

Contents

This listing is designed to help the health care provider focus on possible tests ordered with certain common diseases or conditions The numbers and letters reflect ICD-10 codes, which are described on pp 1 and 2

Testing for Common

Diseases and Conditions

Adrenal Functional Abnormalities:

Testing for Common Diseases and Conditions

Testing for Common Diseases and Conditions xiii

Testing for Common Diseases and Conditions

Testing for Common Diseases and Conditions xv

Testing for Common Diseases and Conditions

Testing for Common Diseases and Conditions xvii

Testing for Common Diseases and Conditions

Testing for Common Diseases and Conditions xix

Sexually Transmitted Diseases:

Testing for Common Diseases and Conditions

CHAPTER

Guidelines for Proper

Test Preparation and

Overview

A complete evaluation of patients with signs or symptoms of disease usually requires a thorough history

and physical examination, as well as efficient diagnostic testing The correct use of diagnostic testing

can confirm or eliminate the presence of disease and improve the cost efficiency of screening tests in a

community of people without signs or symptoms of disease Finally, appropriate and thoughtfully timed

use of diagnostic testing allows monitoring of disease and treatment

Furthermore, health care economics demands that laboratory and diagnostic testing be

per-formed accurately and in a timely fashion Tests should not have to be repeated because of improper

patient preparation, test procedures, or specimen collection technique The following guidelines will

describe the responsibilities of health care providers to ensure safety and accuracy in diagnostic

testing

Patient education is the single most important factor in ensuring accuracy and success of test results

All phases (before, during, and after) of the testing process must be thoroughly explained to the patient

A complete understanding of these factors is essential to the development of nursing processes and

standards of care for diagnostic testing

The interpretation of diagnostic testing is no longer left to the physician alone In today's complex

environment of high-tech testing and economic restrictions, individuals representing many health

care professions must be able to interpret diagnostic tests to develop a timely and effective treatment

plan

CODING FOR DIAGNOSTIC AND LABORATORY TESTS

The International Classification of Diseases, Clinical Modification (ICD-CM) is used to code and

classify disease (morbidity data) The ICD-Procedure Coding System (PCS) is used to code inpatient

procedures “ICD-10” is the abbreviated way to refer to 10th revision of these codes In October

OVERVIEW

Coding for Diagnostic and Laboratory Tests, 1

Laboratory Methods, 2

Standard Precautions, 5

Proper Sequencing and Scheduling of Tests, 5

Procedure and Patient Care, 6

2

2014, use of ICD-10 will be mandated as a HIPAA requirement These codes provide an meric designation for diagnoses and inpatient procedures These codes are developed, monitored, and copyrighted by the World Health Organization In the United States, the NCHS (National Center for Health Statistics) which is part of CMS (Centers for Medicare and Medicaid Services) oversees the ICD codes Using these codes, government health authorities can track diseases and causes of death, and compare mortality All of the patient's diseases and conditions are converted to an ICD code.This information is required for use by third-party health care payers and providers and all points

alphanu-of service Each diagnostic test must reflect the ICD code that most accurately identifies the patient's medical condition Accurate coding is necessary so that data can be accurately collected, testing accurately interpreted, and medical care properly reimbursed Complying with this coding require-ment is no small task because there are there are about 140,000 codes in the ICD-10 catalogs See

p xi for a listing of common codes For additional information about this coding requirement, see

http://www.cdc.gov/nchs/icd/icd10.htm;http://www.cms.gov/Medicare/Coding/ICD10/downloads/ ICD10FAQs.pdf

LABORATORY METHODS

To understand laboratory diagnostic testing, it is helpful to have a basic understanding of commonly performed laboratory methods that can be used on blood, urine, spinal fluid, and other bodily speci-mens Most laboratory diagnostic tests use serologic and immunologic reactions between an antibody

and an antigen Precipitation is a visible expression of the aggregation of soluble antigens Agglutination

is a visible expression of the aggregation of particulate antigens or antibodies As the specimen is gressively diluted, persistent precipitation or agglutination indicates greater concentrations of the anti-gen or antibody Dilution techniques are therefore used to quantify the pathologic antigen or antibody in the specimen Commonly used laboratory methods and their variations are described in the following

pro-Latex Agglutination

Latex agglutination is a common laboratory method in which latex beads (that become visibly obvious when agglutination occurs) are coated with antibody molecules When mixed with the patient's specimen containing a particular antigen, agglutination will be visibly obvious C-reactive proteins are identified by this method In an alternative latex agglutination method (for example, as needed for pregnancy testing

or rubella testing), latex beads are coated with a specific antigen In the presence of antibodies in the patient's specimen to that specific antigen on the latex particles, visible agglutination occurs

of migration Serum protein electrophoresis utilizes this method.

Immunoelectrophoresis Immunoelectrophoresis is a laboratory method that allows the previously electrophoresed proteins to act as antigens to which known specific antibodies are added This provides specific protein identification With dilution techniques as described, these particular proteins can

be quantified This method is used to identify gammopathies, hemoglobinopathies, and Bence Jones proteins

Immunofixation Electrophoresis Immunofixation electrophoresis (IFE) is particularly helpful

in the identification of certain diseases In this method, a specific known antibody is added to a previously electrophoresed specimen The antigen/antibody complexes become fixed (that is attached)

to the electrophoretic gel medium When the non-fixed proteins are washed away, the protein immune complexes that remain fixed to the gel are stained with a protein-sensitive stain and can be identified and quantified IFE is particularly helpful in identifying proteins that exist in very small quantities in the serum, urine, or CSF

Enzyme-Linked Immunosorbent Assay. Enzyme linked immunosorbent assay (ELISA)

tech-niques are able to detect immunocomplexes more easily when compared to RIA This ELISA technique

(also known as enzyme immunoassay [EIA]) is able to detect antigens or antibodies by producing an

enzyme-triggered color change In this method, an enzyme-labeled antibody or antigen is used in the immunologic assay to detect either suspected abnormal antibodies or antigens in the patient's speci-

men In this method, a plastic bead (or a plastic test plate) is coated with an antigen (e.g., virus) The antigen is incubated with the patient’s serum If the patient’s serum contains antibodies to the patho-

logic viral antigen, an immunocomplex forms on the bead (or plate) When a chromogenic chemical

is then added, a color change is noted and can be spectrophotometrically compared with a control (or reference) serum identification Then, quantification of abnormal antibodies in the patient’s serum instigated by the viral infection can be performed Similarly EIA can also be used for detection of pathologic antigens in the patient’s serum Testing for HIV, hepatitis, or cytomegalovirus commonly uses these methods

Autoimmune Enzyme Immunoassay. Autoimmune enzyme immunoassay screening tests are

commonly used for the detection of antinuclear antibodies EIA techniques (similar to what have been described in the preceding) are used as the purified nuclear antigens are bound to a series of microwells

to which the patient's serum is serially diluted and added After adding up peroxidase conjugated antihuman IgG, a complex antibody/antigen “sandwich” is identified by color changes

4

Chemiluminescent Immunoassays. Chemiluminescent immunoassays are extensively used in

automated immunoassays In this technique, chemiluminescent labels can be attached to an antibody

or antigen After appropriate immunoassays are obtained (as described), light emission produced by the immunologic reaction can be measured and quantified This technique is commonly used to detect proteins, viruses, and nucleic acid sequences associated with disease

Fluorescent Immunoassays. Fluorescent immunoassays consist of labeling antibody with

fluorescein This fluorescein-labeled antibody is able to bind either directly with a particular antigen

or indirectly with antiimmunoglobulins Under a fluorescent microscope, the fluorescein becomes

obvious as yellow-green light Testing for Neisseria gonorrhea or antinuclear antibodies may use these

laboratory methods

With the increasing use of automated analyzers, the use of chemiluminescence and nephelometry

has become extremely important to allow analyzers to quantify results in great numbers of specimens

tested in a short period of time Nephelometry (in auto analyzers) depends on the light-scattering

properties of antigen/antibody complexes as light is passed through the test medium The tity of the cloudiness or turbidity in a solution then can be measured photometrically Automated C-reactive protein, alpha antitrypsin, haptoglobins, and immunoglobulins are often measured using nephelometry

quan-Polymerase Chain Reaction

Since the complete human genome sequence became available in 2003, laboratory molecular genetics has become an integral part of diagnostic testing Molecular genetics depends on an in vitro method

of amplifying low levels of specific DNA sequences in a patient specimen to raise quantities of a potentially present specific DNA sequence to levels that can be quantitated by further analysis This process is called Polymerase Chain Reaction (PCR) This is particularly helpful in the identification of diseases caused by gene mutations (e.g., BRCA mutations), in the identification and quantitation of infectious agents such as HPV or HIV, and in the identification of acquired genetic changes that may be present

in hematologic malignancies or colon cancer

In PCR procedures, a known particular target short DNA sequence (ranging from 100 to 1000 nucleotide pairs) is used This known DNA sequence “primer” is then placed in a series of reactions with the patient's specimen These reactions are designed to markedly increase the number of comparable abnormal DNA sequences that potentially exist in the patient's specimen The increased number of abnormal DNA sequences then can be identified and quantified In many instances, the nucleic acid

of interest is ribonucleic acid (RNA) rather than DNA In these circumstances, the PCR procedure is

modified by reverse transcription (reverse transcriptase PCR [RT PCR]) With RT PCR, abnormal RNA

can be amplified (increased in number), detected, and quantified

Real-time PCR uses the same reaction sequence as described In real-time PCR, fluorescence

resonance energy transfer is used to quantitate the DNA sequences of interest and identify points of mutation Real-time PCR provides a product that can be more accurately quantified

Quantification of PCR derived DNA/RNA products can be performed in many ways This can be

performed by simple gel electrophoresis, DNA sequencing, or using DNA probes DNA probes are

presynthesized DNA primers that are used to identify and quantify the amplified DNA produced by

the PCR process Hybridization techniques such as liquid phase hybridization interact with a defined

DNA probe and the potential targeted DNA in solution DNA probes have become a very important

part of commercial laboratory molecular genetics Microarray DNA chip technology (Microarray analysis) places thousands of major DNA probes on one glass chip After interaction with the pa-

tient’s specimen, the microarray chip can then be scanned with high speed fluorescent detectors that

Overview 5

can quantify each DNA micro sequence This process is used to identify gene expression of

malig-nancies and has led to a new understanding of the classification, pathophysiology, and treatment of cancer

Fluorescence in Situ Hybridization (FISH)

Fluorescence in situ hybridization (FISH) uses nucleic probes (short sequences of single-stranded DNA) that are complementary to the DNA sequence to be identified These nucleic probes are labeled with fluorescent tags that can identify the exact location of the complementary DNA sequence that is being targeted This method is particularly helpful in the detection of inherited and acquired chromo-

somal abnormalities common in hematologic and other oncologic conditions, such as lymphomas and breast cancer Laboratory genetics are also discussed on p 1104

STANDARD PRECAUTIONS

The risk of spread of diseases such as hepatitis B virus (HBV) and human immunodeficiency virus (HIV) has made all health care organizations aware of the need to protect health care providers These threats prompted the Centers for Disease Control and Prevention (CDC) to release its guide-

that blood and body fluid precautions be used for all patients regardless of their infection status All patients should be considered potentially infectious The Standard Precautions apply to all blood, body fluids, and tissues Serous fluids such as pleural, peritoneal, amniotic, cerebrospinal, and syno-

vial fluids are included Semen and vaginal secretions should also be considered hazardous Other clinical specimens (e.g., sputum, stool, urine) are of less concern, and the Standard Precautions apply only if these specimens contain visible amounts of blood

These precautions require the use of protective barriers (gloves, gowns, masks, protective eyewear)

to avoid skin and mucous membrane exposure to blood and body fluids A fundamental principle of Standard Precautions is frequent handwashing between patients and when gloves are changed All spec-

imens should be collected and transported in containers that prevent leakage Blood or body fluid spills must be decontaminated immediately All needles and other sharp items must be handled carefully and discarded in puncture-resistant containers Needles should not be recapped, broken, bent, or removed from a syringe to avoid the risk of puncturing the finger or hand All needle sticks need to be reported and followed up with appropriate testing for infectious disease Special reusable needles are placed in metal containers for transport to a designated area for sterilization or disinfection

Vaccination against HBV is another safety precaution recommended by the CDC

PROPER SEQUENCING AND SCHEDULING OF TESTS

Because of the cost and complexity of laboratory and diagnostic testing, it is important that tests be scheduled in the most efficient sequential manner Because one type of test can interfere with another, certain guidelines apply when multiple tests must be performed in a limited amount of time X-ray examinations that do not require contrast material should precede examinations that do require contrast media X-ray studies using barium should be scheduled after ultrasonography studies For example, x-ray studies using barium should follow x-rays using iodine contrast dye (such as intravenous pyelography [IVP]), which should follow x-ray studies using no contrast because contrast agents can obscure visualization of other body areas on subsequent x-ray tests Also, stool specimens should be collected before x-ray studies using barium

6

Test sequencing affects the ability to efficiently perform tests in a limited time period An essential component of this process is communication and collaboration with other health care workers in numerous departments

PROCEDURE AND PATIENT CARE

Before the Test

Patient preparation is vital to the success of any diagnostic test Patient education is essential and is discussed later in this chapter Development of and adherence to patient care guidelines in regard to pa-tient preparation for the test require an understanding of the procedure A thorough history to identify contraindications to the specific test is vital Recognizing patients at risk for potential complications and counseling them about those complications is important The fears and concerns of the patient should

be elicited and addressed prior to testing Documentation and a thorough understanding of ongoing factors (e.g., medications, previous tests, other variables as discussed later in this chapter) that could interfere with the test results are essential to avoid misinterpretation of diagnostic testing

Pretest preparation procedures must be followed closely Dietary restriction is often an important factor in preparing the patient for tests Studies requiring fasting should be performed as early in the

BOX 1-1 Standard Precautions

These precautions have been mandated by

the Occupational Safety and Health

Admin-istration (OSHA) Their purpose is to protect

health care workers from contracting

illnesses from the specimens they handle,

the patients they care for, and the environment

in which they work The precautions are as

follows:

• Wear gowns, gloves, protective eyewear,

face masks, and protective clothing

(including laboratory coat) whenever

exposed to blood or other body fluids.

• If the health care worker's skin is opened,

gloves should be worn whenever direct

patient care is performed.

• Mouth-to-mouth emergency resuscitation

equipment should be available in strategic

locations The mouthpieces should be

individualized for each health care worker

Ambu bags are preferable Saliva is

considered an infectious fluid.

• Dispose of all sharp items in

puncture-resistant containers.

• Do not “recap,” bend, break, or remove

needles from syringes.

• Immediately remove gloves that have a

hole or tear in them.

• All disposed patient-related wastes must

• Assume that every person is potentially infected or colonized with an organism that could be transmitted in the health care setting.

• Implement respiratory hygiene/cough etiquette instructions to contain respiratory secretions in patients and accompanying individuals who have signs and symptoms

of a respiratory infection These include posting signs with instructions about covering mouths/noses, using and disposing of tissues, and hand hygiene Offer masks to coughing patients and encourage them to keep a distance of at least three feet from others.

• If a health care worker has experienced an exposure incident to blood or other body fluids (e.g., needle stick), testing of the health care worker and the patient for HBV and HIV is necessary.

Data from Centers for Disease Control and Prevention, 2007.

Equally important to total patient care is the coordination of ongoing therapy (e.g., physical therapy, administration of medications, other diagnostic testing) Finally, correct timing of testing is key to accurate interpretation of results For example, blood samples for cortisol, parathormone, and fasting glucose levels (among others) must be obtained in the early morning hours.

Patient Identification Proper identification of the patient is a critical safety factor The conscious patient should be asked to state his or her full name The name should be verified by checking the identification band and requisition slip The identity of an unconscious patient should be verified

by family or friends No specimens should be collected or procedure performed without properly identifying the patient Costly tests on the wrong patient are useless and may instigate legal action Confusion can occur when patients with the same name are on the same nursing unit Most units have some type of warning or “name alert” to address this concern

Patient Education Once the patient is properly identified and the proper test or procedure is scheduled, patient education begins Patients want to know what tests they are having and why they are needed An informed patient is less apprehensive and more cooperative Patient education helps ensure that the test will not need to be repeated because of improper preparation Fasting requirements

and bowel preparations must be clearly explained to the patient Written instructions are essential

If used, the patient's literacy and understanding of the material should be validated Sometimes medications need to be discontinued for a period of time before certain tests This information should

be determined in consultation with the physician Medications that are not discontinued may be listed on the requisition to aid in interpretation of test results Finally it is extremely important to inform the patient regarding the need to discontinue medications or foods that may interfere with testing results

Variables Affecting Test Results Many laboratory tests are affected by individual variables that must be considered in test result interpretation Several of these key variables are discussed in the following paragraphs

Age Pediatric reference values differ from adult values For some tests, values vary according to the week of life of the infant For example, in the first week of life, newborns have elevated levels of serum

bilirubin, growth hormone, blood urea nitrogen (BUN), and fetal hemoglobin They have decreased levels of cholesterol and haptoglobin Healthy newborns also have an increase in total white blood cells

and decreases in immunoglobulin (Ig) M and IgA For some tests, children have different reference values based on their developmental stage For example, alkaline phosphatase levels in children are much higher than adult values because of rapid bone growth

Age-related changes are also apparent in the middle adult and older adult years For example,

albu-min and total protein levels begin to decline in the mid-adult years Reference values for cholesterol and

triglyceride levels begin to increase in the mid-adult years Creatinine clearance levels decrease with age

relative to changes in glomerular filtration rate

8

Gender Gender is another variable that affects values in men and women Differences are usually related to increased muscle mass in men and differences in hormonal secretion For example, men usually have higher reference values for hemoglobin, BUN, serum creatinine, and uric acid Men also have higher serum levels of cholesterol and triglycerides as compared with premenopausal women Sex-specific hormones will also differ, with men having higher testosterone levels and women having higher levels of estrogens, follicle-stimulating hormone, and luteinizing hormones

Race Generally race has little effect on laboratory values It has a greater effect on genetic diseases, such

as sickle cell anemia in blacks and thalassemia in individuals with origins near the Mediterranean Sea

Pregnancy Many endocrine, hematologic, and biochemical changes occur during pregnancy Pregnant women have increased levels of cholesterol, triglycerides, lactic dehydrogenase, alkaline phosphatase, and aspartate aminotransferase They may have lower values of hemoglobin, hematocrit, serum creatinine, urea, glucose, albumin, and total protein

Food Ingestion Several serum values are markedly affected by food For example, levels of glucose and triglycerides rise after a meal To avoid the effects of diet on laboratory tests, many tests are obtained when the patient is in the fasting state

Posture Changes in body position affect the concentration of several components in the peripheral blood Therefore it is sometimes important to note whether the patient was in the supine, sitting, or standing position when blood was drawn Examples of laboratory values affected by posture include norepinephrine, epinephrine, renin, aldosterone, protein, and potassium

Transport and Processing of the Specimen Preparing the patient and collecting the specimen are essential Getting the specimen to the laboratory in an acceptable state for examination is just

as important In general, the specimen should be transported to the laboratory as soon as possible after collection Delays may result in rejection of the specimen Specimens are usually refrigerated if transportation is delayed

A Note About SI Units The International System of Units (SI units) is a system for reporting laboratory values in terms of standardized international measures This system is currently used in many countries, and it is expected to be adopted worldwide Throughout this book results are given in conventional units and SI units when possible

Overview 9

After the Test

Posttest care is an important aspect of total patient care Attention should be directed to the patient's concerns about possible results or the difficulties of the procedure Appropriate treatment subsequent to testing must be provided For example, after a barium test, a cathartic is indicated However, if a bowel obstruction has been identified, catharsis is contraindicated

Recognition and rapid institution of treatment of complications (e.g., bleeding, shock, bowel

perfo-ration) is essential in caring for the patient who has just had a diagnostic procedure More invasive tests often require heavy sedation or a surgical procedure In these situations, aftercare is similar to routine postoperative care

Reporting Test Results Although proper patient preparation and skill and accuracy in performing test procedures are vital, timeliness in reporting test results is no less essential To be clinically useful, results must be reported promptly Delays in reporting test results can make the data useless The data must be included in the appropriate medical record and presented in a manner that is clear and easily interpreted As in all phases of testing, communication among health care professionals is important Health care providers need to understand the significance of test results For example, nurses on the evening shift may be the first to see the results of a culture and sensitivity report on a patient with a urinary tract infection If the results indicate that the infecting organism is not sensitive to the prescribed antibiotic, the doctor should be informed and an appropriate antibiotic order obtained

Ethical standards for disclosure of test results must be strictly followed In 1996, the Health

Insur-ance Portability and Accountability Act (HIPAA) became law Its purpose was to improve the health care of each individual by insuring the ability for each person to obtain reasonable health care, and

to allow each individual access to and protection of his or her health care information In response to

the HIPAA mandate, Health and Human Services published the Standards for Privacy of Individually Identifiable Health Information (the Privacy Rule) in December 2000, which became effective on April

14, 2001 The Privacy Rule set national standards for the protection of an individual's health

infor-mation Compliance with this rule is particularly important when providing diagnostic test results The Privacy Rule generally gives patients the right to examine and obtain a copy of their own health records and to request corrections It limits who can have access to results of diagnostic tests Infor-

mation regarding test results can only be provided to the patient and to persons the patient indicates (by signature) Only health care workers who have a provider relationship with a patient may obtain access to a patient's test results The federal government has responsibility for enforcing these laws and violators are subject to civil and criminal prosecution Fines can be levied against both the individual and the health organization The penalties for violation of these laws are fines up to $250,000 and

up to 10 years in jail

As a result of the Privacy Rule, test results are not given over the phone to patients Results, no matter if normal or not, are never left on “answering machines.” Results cannot be given to family or friends unless written consent is provided These restrictions include providing test results to spouses, parents of adult children, siblings, or children If the patient presents in the laboratory or a clinical area, the patient is usually required to show a photo identification to confirm his or her identity and to verify his or her signature on a Release of Information Authorization form The Privacy Rule does not negate state regulations that affect test result reporting For example, in most states, HIV results are released only to the ordering physician/provider and are not provided by the laboratory to the patient Compliance with the Privacy Rule is an extremely important part of diagnostic testing and patient education The impact of an abnormal test result on the patient must always be appreciated, and sup-

port must be provided

10

Knowledge of the implications of various test results and an understanding of the disease process are as important as the communicative skills required to inform the patient and the family Succinct documentation of test results may be required before the “official” result is included in the patient's chart Again, a thorough understanding of the test is essential Adequate follow-up is as important as all previously mentioned factors for successful diagnostic testing The patient must be educated about home care, the next doctor's visit, and treatment options

•  •  •Knowledgeable interpretation of diagnostic tests is key for effective collaboration among health care providers if the most efficient patient care is to be provided The safety and success of diagnostic testing often depend on the nurse and other health care professionals The safety of the patient and health care professionals depends on the creation of practice guidelines and standards of care These can be effectively developed only with a thorough understanding of laboratory and diagnostic testing

CHAPTER

OVERVIEW

Reasons for Obtaining Blood Studies, 14

Methods of Blood Collection, 14

Timing of Blood Collection, 21

Transport and Processing of Blood Specimens, 21

Reporting of Results, 22

TESTS

Acetylcholine Receptor Antibody Panel, 23

Acid Phosphatase, 25

Activated Clotting Time, 27

Adrenal Steroid Precursors, 29

Adrenocorticotropic Hormone, 31

Adrenocorticotropic Hormone Stimulation, 34

Adrenocorticotropic Hormone Stimulation

Antidiuretic Hormone Suppression, 76Anti-DNA Antibody, 78

Antiextractable Nuclear Antigen, 79Antiglomerular Basement Membrane Antibody, 81

Anti-Glycan Antibodies, 82Anti-Liver/Kidney Microsomal Type 1 Antibodies, 83

Antimitochondrial Antibody, 84Antimyocardial Antibody, 86Antineutrophil Cytoplasmic Antibody, 87Antinuclear Antibody, 88

Anti–Parietal Cell Antibody, 92Antiscleroderma Antibody, 93Anti–Smooth Muscle Antibody, 95Antispermatozoal Antibody, 96Anti–SS-A, Anti–SS-B, and Anti–SS-C Antibody, 98Antistreptolysin-O Titer, 470Antithrombin Activity and Antigen Assay, 100

Antithyroglobulin Antibody, 102Antithyroid Peroxidase Antibody, 104Apolipoproteins, 106

Arterial Blood Gases, 109Aspartate Aminotransferase, 119

Continued

Coombs Test, Direct, 175

Coombs Test, Indirect, 177

Drug Sensitivity Genotype Testing, 216

Epstein-Barr Virus Testing, 217

Fetal Hemoglobin Testing, 237Fetal Scalp Blood pH, 239Fibrinogen, 241

Folic Acid, 242Galectin-3, 245Gamma-Glutamyl Transpeptidase, 246Gastrin, 248

Gliadin Antibodies, 250Glucagon, 251

Glucose, Blood, 253Glucose, Postprandial, 257Glucose-6-Phosphate Dehydrogenase, 259Glucose Tolerance, 261

Glycosylated Hemoglobin, 266Growth Hormone, 269Growth Hormone Stimulation, 272Haptoglobin, 274

Heinz Body Preparation, 275Hematocrit, 277

Hemoglobin, 281Hemoglobin Electrophoresis, 284Hepatitis Virus Studies, 286Hexosaminidase, 290HIV Drug Resistance Testing, 292HIV RNA Quantification, 294HIV Serologic and Virologic Testing, 297Homocysteine, 301

Human Chorionic Gonadotropin, 304Human Lymphocyte Antigen, 306Human Placental Lactogen, 308Human T-Cell Lymphotrophic Virus, 31021-Hydroxylase Antibodies, 311

Immunoglobulin Quantification, 312Insulin Assay, 315

Insulin-like Growth Factor, 317Intrinsic Factor Antibody, 320Iron Level, Total Iron-Binding Capacity, Transferrin, Transferrin Saturation, 322

TESTS—cont’d

Maternal Screen Testing, 354

Metanephrine, Plasma Free, 357

Methemoglobin, 359

Microglobulin, 360

Mononucleosis Rapid Test, 363

Mycoplasma pneumoniae Antibodies, IgG

and IgM, 364

Myoglobin, 365

Natriuretic Peptides, 367

Neuron-Specific Enolase, 369

Neutrophil Antibody Screen, 370

Neutrophil Gelatinase–Associated Lipocalin,

Progesterone Assay, 416Prolactin Level, 418Prostate Specific Antigen, 420Protein, 424

Protein C, Protein S, 432Prothrombin Time, 434Rabies-Neutralizing Antibody, 438Red Blood Cell Count, 439Red Blood Cell Indices, 442Renin Assay, Plasma, 447Reticulocyte Count, 452Rheumatoid Factor, 454Ribosome P Antibodies, 456Rubella Antibody, 457Rubeola Antibody, 459Septin 9 DNA Methylation Assay, 460Serotonin and Chromogranin A, 462Sickle Cell Screen, 464

Sodium, Blood, 466Squamous Cell Carcinoma Antigen, 469

Streptococcus Serologic Testing, 470

Syphilis Detection, 473Testosterone, 476Thromboelastography, 479Thrombosis Indicators, 482Thyroglobulin, 484

Thyroid-Stimulating Hormone, 486Thyroid-Stimulating Hormone Stimulation, 489

Thyroid-Stimulating Immunoglobulins, 491Thyrotropin-Releasing Hormone Stimulation Test, 492

Thyroxine-Binding Globulin, 495Thyroxine, Total and Free, 497Toxoplasmosis Antibody Titer, 500Transferrin Receptor Assay, 502Triglycerides, 504

Triiodothyronine, 506Troponins, 508Urea Nitrogen, Blood, 511

TESTS—cont’d

Continued

West Nile Virus Testing, 524

White Blood Cell Count and Differential Count, 526

d-Xylose Absorption, 533Zinc Protoporphyrin, 534

TESTS—cont’d

Overview

REASONS FOR OBTAINING BLOOD STUDIES

Blood is the body fluid most frequently used for analytic purposes Blood studies are used to assess

a multitude of body processes and disorders Common studies assess the quantity of red and white blood cells, and the levels of enzymes, lipids, clotting factors, and hormones Most blood studies are performed for one of the following reasons:

1 To establish a diagnosis (e.g., high blood urea nitrogen [BUN] and creatinine levels are indicative

of renal failure)

2 To rule out a clinical problem (e.g., hypokalemia is ruled out with a normal potassium level).

3 To monitor therapy (e.g., glucose levels are used to monitor treatment of diabetic patients, and

partial thromboplastin time [PTT] values are used to regulate heparin therapy)

4 To establish a prognosis (e.g., declining CD4 counts reflect a poor clinical prognosis for the

acquired immunodeficiency syndrome [AIDS] patient)

5 To screen for disease (e.g., prostate-specific antigen levels are used to detect prostate cancer).

6 To determine effective drug dosage and to prevent toxicity (Peak and trough levels are drawn at

designated time periods; see p 21.)

METHODS OF BLOOD COLLECTION

There are three general methods for obtaining blood: venous, arterial, and skin puncture Blood

collect-ed from these sites differs in several important aspects For example, arterial blood is oxygenatcollect-ed by the lungs and pumped from the heart to body organs and tissues It is essentially uniform in its composition throughout the body Venous blood composition varies depending on the metabolic activity of the organ

or tissue being perfused Venous blood is oxygen-deficient in comparison to arterial blood Variations

glu-cose, lactic acid, and ammonia levels On the other hand, blood obtained by skin puncture is a mixture

of arterial and venous blood Skin puncture blood also includes intracellular and interstitial fluid By far the most common access for blood withdrawal is venous puncture

Venous Puncture

Background Information The ease of obtaining venous blood makes this the primary source of blood collection It is relatively free of any complications Venipuncture is usually obtained by drawing

fossa of the arm because there are several large superficial veins at that location The basilic, cephalic, and median cubital veins are the most commonly used sites Veins of the wrist or hand can also be used

on the tests needed, the analysis is performed on whole blood, serum, or plasma A centrifuge is used

to separate the blood components and to obtain either serum or plasma Whole blood collected without

anticoagulant clots, and serum can be separated out for testing Whole blood collected with an anticoagulant prevents clotting, and plasma can be tested Plasma contains fibrinogen, which is missing from serum.

The selection of the color-coded tube is based on the requirements of the test Charts are available from the laboratory that indicate the type of tube needed for a particular blood test Colors and amount

The recommended order of draw must be followed when collecting multiple tubes of blood

Speci-mens should be drawn into nonadditive tubes (e.g., red top) before tubes are drawn that contain

addi-tives The tubes should be filled in the following order:

1 Blood culture tubes first (to maintain sterility)

2 Nonadditive tubes (e.g., red top)

3 Coagulation tubes (e.g., blue top)

4 Heparin tubes (e.g., green top)

5 EDTA-K3 tubes (e.g., lavender top)

6 Oxalate-fluoride tubes (e.g., gray top)

16

TABLE 2-1 Blood Studies

Red None To allow blood sample to

clot This permits separation

of serum when the serum needs to be tested

Chemistry, Bilirubin, Blood urea nitrogen (BUN), Calcium

Red/black None Serum separator tube for

serum determinations in chemistry and serology

oxalate To prevent glycolysis Chemistry, Glucose, Lactose tolerance Green Heparin To prevent blood from

clotting when plasma needs to be tested

Chemistry, Ammonia, Carboxyhemoglobin

Blue Sodium citrate To prevent blood from

clotting when plasma needs to be tested

Hematology Prothrombin time (PT), Partial throm- boplastin time (PTT) Black Sodium citrate Binds calcium to prevent

blood clotting Westergren erthrocyte sedimentation rate (ESR) Yellow Citrate dextrose Preserves red cells Blood cultures

Gold serum

separator

tube (SST)

None Collects serum Chemistry

Figure 2-2 Supplies for venipuncture: tourniquet, Vacutainer and needle, specimen tubes, skin preparation antiseptics, protective gloves, gauze, Band-Aid.

Perform the venipuncture by entering the skin with the needle bevel up and the needle at approxi-mately a 15-degree angle to the skin.

• If using a Vacutainer, ease the tube forward in the holder as soon as the needle is in the vein When the tube is filled, remove it Another tube can then be inserted into the holder If using a syringe, pull back

on the barrel with slow, even tension as blood fills the syringe Transfer the blood to the appropriate color tubes Butterfly needles can also be used for collection

• Release the tourniquet when the blood begins to flow

After

• After the blood is drawn, place a cotton ball over the site Withdraw the needle and apply pressure to the site A Band-Aid applied over the cotton ball usually stops the bleeding

• Mix tubes with the additives by gently rolling the tubes Do not vigorously shake the tubes Specimens collected in the syringe should be transferred to appropriate test tube containers

18

Potential Complications

• Bleeding After the specimen is drawn, apply pressure or a pressure dressing to the venipuncture site

Assess the venipuncture site for bleeding

• Hematoma Hematomas can form under the skin when the vein continues to leak blood This results

in a large, bruised area This can usually be prevented by applying pressure to the venipuncture site until clotting occurs If a hematoma does occur, reabsorption of the blood can be enhanced by the application of warm compresses

• Infection Instruct the patient to assess the venipuncture site for redness, pain, swelling, or

tender-ness This is more common in immunocompromised patients or patients who have had lymph node dissection above the venipuncture site

• Dizziness and fainting If this occurs, prevent injury by helping the patient to a sitting or reclining

position Lowering the head between the knees or using smelling salts can also help

Preventing Interfering Factors

• Hemolysis may result from vigorous shaking of a blood specimen This may invalidate test results

• Collect the blood specimen from the arm without an intravenous (IV) device if possible IV infusion can influence test results If it is necessary to draw blood from the arm with an IV device, never draw blood above the IV needle site Satisfactory samples may be obtained by drawing the blood below the

IV needle after turning the IV infusion off for 2 minutes before the venipuncture Select a vein other than the one with the IV device and draw 5 mL of blood Discard this sample before drawing blood for analysis

• Do not use the arm with the dialysis arteriovenous fistula for a venipuncture unless the physician specifically authorizes it

• Because of the risk for cellulitis, specimens should not be taken from the side on which an axillary lymph node dissection has been performed

• To obtain valid results, do not fasten the tourniquet for longer than 1 minute Prolonged tourniquet application can cause stasis, localized acidemia, and hemoconcentration

Drawing Blood from an Indwelling Venous Catheter Follow the institutional guidelines for drawing blood from an indwelling venous catheter, such as a central venous catheter or a peripherally inserted central catheter Guidelines will specify the amount of blood to be drawn from the catheter and discarded before blood is collected for laboratory studies The guidelines also indicate the amount and type of solution needed to flush the catheter to prevent it from being clogged by blood

Drawing a Panel of Blood Studies Blood tests are often part of a panel or group of specified tests This is because patterns of abnormalities may be more useful than single test changes See Appendix C for blood tests included in disease and organ panels

Arterial Puncture

Background Information Arterial blood is used to measure oxygen, CO2, and pH These are often referred to as arterial blood gases (ABGs) and are described on p 109 If a patient will require frequent sampling, an indwelling arterial catheter is usually placed Arterial puncture is used for single

or infrequent sampling

Arterial punctures are more difficult to perform than venipuncture They also cause a significant amount of patient discomfort The brachial and radial arteries are the arteries most often used for arterial puncture The femoral artery is usually avoided because bleeding occurs more often after the procedure and may not be noted because it is hidden by bed covers Large amounts of blood could be lost before the problem is detected

• Perform the Allen test to assess collateral circulation before performing the arterial puncture on the

radial artery To perform the Allen test, make the patient's hand blanch by obliterating both the radial and ulnar pulses Then release the pressure over the ulnar artery only If flow through the ulnar artery is good, flushing will be observed immediately The Allen test is then positive and the radial artery can be used for venipuncture If the Allen test is negative (no flushing), repeat it on the other arm If the results are negative in both arms, choose another artery for puncture The Allen test is important because it ensures collateral circulation to the hand if thrombosis of the radial artery occurs after the puncture

If the patient has an abnormal clotting time or is taking anticoagulants, apply pressure for approxi-mately 15 minutes A pressure dressing is usually applied

Figure 2-4 Drawing arterial blood Note that the needle is at a 45-degree angle.