Chapter 045. Azotemia and Urinary Abnormalities (Part 1) pot

The duration and severity of the disease will affect these findings and typically include one or more of the following: 1 disturbances in urine volume oliguria, anuria, polyuria; 2 abnor

Chapter 045 Azotemia and Urinary Abnormalities

(Part 1)

Harrison's Internal Medicine > Chapter 45 Azotemia and Urinary Abnormalities

Azotemia and Urinary Abnormalities: Introduction

Normal kidney functions occur through numerous cellular processes to maintain body homeostasis Disturbances in any of these functions can lead to a constellation of abnormalities that may be detrimental to survival The clinical manifestations of these disorders will depend upon the pathophysiology of the renal injury and will often be initially identified as a complex of symptoms, abnormal physical findings, and laboratory changes that together make possible the identification of specific syndromes These renal syndromes (Table 45-1) may

arise as the consequence of a systemic illness or can occur as a primary renal disease Nephrologic syndromes usually consist of several elements that reflect the underlying pathologic processes The duration and severity of the disease will affect these findings and typically include one or more of the following: (1) disturbances in urine volume (oliguria, anuria, polyuria); (2) abnormalities of urine sediment [red blood cells (RBC); white blood cells, casts, and crystals]; (3) abnormal excretion of serum proteins (proteinuria); (4) reduction in glomerular filtration rate (GFR) (azotemia); (5) presence of hypertension and/or expanded total body fluid volume (edema); (6) electrolyte abnormalities; or (7) in some syndromes, fever/pain The combination of these findings should permit identification of one of the major nephrologic syndromes (Table 45-1) and will allow differential diagnoses to be narrowed and the appropriate diagnostic evaluation and therapeutic course to be determined Each of these syndromes and their associated diseases are discussed in more detail in subsequent chapters This chapter will focus on several aspects of renal abnormalities that are critically important to distinguishing among these processes: (1) reduction in GFR leading

to azotemia, (2) alterations of the urinary sediment and/or protein excretion, and (3) abnormalities of urinary volume

Table 45-1 Initial Clinical and Laboratory Data Base for Defining Major Syndromes in Nephrology

Syndromes Important

Clues to Diagnosis

Findings

Common

Locati

Discussion of Disease-Causing Syndrome

Acute or

rapidly progressive

renal failure

Anuria

Oliguria

Documented recent decline in GFR

Hypertensi

on, hematuria

Proteinuria , pyuria

Casts, edema

Chaps

273, 277, 279,

283

Acute

nephritis

Hematuria, RBC casts

Azotemia, oliguria

Edema,

Proteinuria

Pyuria

Circulatory congestion

Chap

277

hypertension

Chronic renal

failure

Azotemia for

>3 months

Prolonged symptoms or signs of uremia

Symptoms or signs of renal osteodystrophy

Kidneys reduced in size bilaterally

Broad casts in urinary sediment

Proteinuria

Casts

Polyuria, nocturia

Edema, hypertension

Electrolyte disorders

Chaps

272, 274

Nephrotic

syndrome

Proteinuria

>3.5 g per 1.73 m2 per

Casts

Lipiduria

Chap

277

24 h

Hypoalbumine mia

Edema

Hyperlipidemi

a

Asymptomati

abnormalities

Hematuria

Proteinuria (below nephrotic range)

Sterile pyuria, casts

Chap

277

Urinary tract

infection/pyelonephr

itis

Bacteriuria >10

5

colonies per milliliter

Other

Hematuria

Mild azotemia

Mild

Chap

282

infectious agent documented in urine

Pyuria, leukocyte casts

Frequency, urgency

Bladder tenderness, flank tenderness

proteinuria

Fever

Renal tubule

defects

Electrolyte disorders

Polyuria, nocturia

Renal calcification

Large kidneys

Renal transport

Hematuria

"Tubular"

proteinuria (<1 g/24 h)

Enuresis

Chaps

278, 279

defects

Hypertension Systolic/diastol

ic hypertension

Proteinuria

Casts

Azotemia

Chaps

241, 280

Nephrolithias

is

Previous history of stone passage or removal

Previous history of stone seen

by x-ray

Renal colic

Hematuria

Pyuria

Frequency, urgency

Chap

281

Urinary tract

obstruction

Azotemia, oliguria, anuria

Polyuria,

Hematuria

Pyuria

Enuresis,

Chap

283

nocturia, urinary retention

Slowing of urinary stream

Large prostate, large kidneys

Flank tenderness, full bladder after voiding

dysuria

Note: GFR; glomerular filtration rate; RBC, red blood cell.