Ebook Pathophysiology flash cards: Part 2

Part 2 book “Pathophysiology flash cards” has contents: Endocrine system, reproductive system and urologic disorders, immune system, hematologic disorders, oncologic disorders, musculoskeletal, integumentary, and connective tissue disorders.

A 46-year-old male presents to his primary care physician with a complaint oftrouble sleeping He states that he lies in bed for up to 3 hours before fallingasleep but does not have problems staying asleep Further questioning revealsthat the patient lost his job 5 months ago and his family has been relying on hiswife’s part-time income He states that he has been feeling depressed for the pastseveral months, as he has not been able to find another source of employment tosupport his family He feels it is hopeless to continue to find a job, and nowspends most of his time now on the couch watching TV He has no interest inactivities he used to enjoy He reports a decreased appetite but denies weightloss, problems concentrating, substance abuse, or suicidal ideations His onlypast medical history includes stage I hypertension well controlled withhydrochlorothiazide Physical examination reveals an appropriately dressed malewith a restricted affect and linear thought process

This patient has major depressive disorder Although there are often severalcriteria for many diagnoses in psychiatry, it is important to first commit tomemory the time requirements and number of symptoms For major depressivedisorder, five symptoms must be present, one of which must be either depressed

mood or anhedonia (lack of Interest), for a minimum of 2 weeks The rest of the nine possible symptoms are Sleep disturbance, feelings of worthlessness or inappropriate Guilt, lack of Energy, diminished Concentration, change in

A 27-year-old female medical student is brought to the emergency department byher roommate who is concerned about her lack of sleeping The patient has notslept in 2 days and has been frantically cleaning their apartment The roommatealso states that the patient has been acting unusually promiscuous over the pastweek and accumulated thousands of dollars in credit card charges buying newclothes The patient states she feels great and just has not been feeling tired Herpast history is significant for one suicide attempt at 17 years after breaking upwith a boyfriend She was subsequently treated with fluoxetine for 2 years butcurrently takes no medications On examination, the patient is hyperverbal withpsychomotor agitation and reports that she is on the verge of discovering thecure for cancer

This patient has bipolar I disorder This diagnosis requires the presence of atleast one manic episode, usually with a history indicative of one or moreepisodes of major depressive disorder A manic episode consists of at least 1week of an abnormally elevated, expansive, or irritable mood or a required

hospitalization with at least three symptoms Symptoms include distractibility,

insomnia or decreased need for sleep, grandiosity (inflated self-esteem), flight of

ideas (racing thoughts), psychomotor agitation or increase in goal-directed activities, pressured speech, and risk-taking (activities involving pleasure with

painful consequences, i.e., excessive spending, sexual indiscretion, gambling) A

useful mnemonic is DIG FAST For bipolar I disorder, the mood disturbance

must be sufficient enough to cause social or occupational impairment, requireshospitalization, or has psychotic features If this is not the case, but at least threesymptoms with mood change have been present for at least 4 days, it isconsidered a hypomanic episode and the diagnosis would be bipolar II disorder

It is important to distinguish the symptoms from personality disorders, as thepersonality disorders are reported under axis II diagnoses

An 11-year-old boy is brought to the pediatrician by his mother, who isconcerned about his behavior She states he has become increasingly rebellioussince his parents divorced 3 years ago He was recently suspended for makingfun of a smaller classmate and his mother often receives calls from the teacherfor talking back He refuses to do his homework and is verbally abusive to hismother Physical examination reveals a slightly overweight boy, appropriatelydressed with normal affect, and linear thought process without psychomotoragitation

This patient is presenting with oppositional defiant disorder This ischaracterized by ongoing defiant and hostile behavior toward authority figures.This differs from conduct disorder in that there are not serious violations ofsocial norms, such as physical altercations, property destruction, animal cruelty,theft, or other activities that might rise to the level of concern to lawenforcement Conduct disorder also often progresses to antisocial personalitydisorder after 18 years of age Other considerations might be separation anxietydisorder following the loss of an attachment figure in the divorce, whichtypically starts at around 7 to 8 years of age

A 36-year-old male is presented at the emergency department by the policebecause he was found standing on the side of the highway The patient claimsthat he felt like he was unable to move and he does not remember how long hewas standing there He thinks that FBI agents have been following him for thepast 6 months, and he does not feel safe at home anymore He also admits tohaving intermittent thoughts of committing suicide During the interview, hementions that his thoughts of suicide are augmented due to the voices telling him

to “end it.” The patient’s past medical history is significant only for controlled type 2 DM His vital signs on admission are heart rate is 78/min,respiratory rate is 16/min, blood pressure is 118/82 mm Hg, temperature is36.7°C (98.1°F), and oxygen saturation is 99% On further examination, thepatient displays flat affect, paranoia, tangential and illogical thought processes,and disorganized speech Urine drug screening is negative for illicit substances

well-

This patient meets the DSM-IV criteria for schizophrenia, which requires more

than 6 months of disturbed functioning with at least 1 month of at least two ofthe following symptoms (unless delusions are bizarre or voices provide runningcommentary, then only one criterion is needed): delusions, hallucinations,disorganized behavior/catatonia, disorganized speech, and negative symptoms.These symptoms arise from a decrease in dopaminergic activity Negativesymptoms (anhedonia, flat affect, avolition) stem from the frontal corticalregion, whereas positive symptoms (delusions and hallucinations) arise from themesolimbic system Typical treatment consists of dopamine antagonists.However, due to high incidence of tardive dyskinesia and extrapyramidalsymptoms associated with D2 dopamine receptor blockade in typicalantipsychotics, atypical antipsychotics are usually the first-line pharmacotherapy

A 23-year-old male is brought to a psychiatrist by his mother She reports he hasbeen behaving strangely since he graduated from college 3 months ago Hestopped socializing with his friends and now spends the entire day in his room.Upon questioning, he is reluctant to answer simple questions He eventuallyreveals that God has been speaking to him and providing him instructions forcreating a device, which will allow him to read other people’s thoughts.Examination reveals an unkempt, disheveled male with restricted affect andcircumstantial thought process Urine drug screening was negative

This patient has schizophreniform disorder The length of time of continuoussigns of disturbance differentiates the disorders presenting with symptoms ofschizophrenia Brief psychotic disorder denotes less than 1 month of symptoms,usually related to stress More than 1 but less than 6 months of disturbedbehavior including occupational/social declines or negative symptoms including

1 month of psychotic symptoms is classified as schizophreniform disorder.Symptoms persisting for more than 6 months indicate schizophrenia.Schizophrenia criteria plus major depression, manic episodes, or both indicates adiagnosis of schizoaffective disorder It is important to distinguish axis Idisorders from the schizoid and schizotypal personality disorders that are part ofaxis II

A 34-year-old woman is being seen in the emergency department for chest painthat started 2 hours ago She states it came on quickly and lasted less than 20minutes The event was accompanied by palpitations, sweating, and shortness ofbreath She currently has no pain or other symptoms Earlier in the evening shehad an argument with her boyfriend She has had one similar episode in the past,but it resolved in 10 minutes and she did not seek medical attention She takes aPPI for mild GERD Her blood pressure is 128/78 mm Hg, pulse is 84/min,respiratory rate is 14/min, and temperature is 37.5°C (99.5°F) She has a normal

S1 and S2 without additional heart sounds, murmurs, or rubs Chest is clear toauscultation bilaterally ECG shows a normal sinus rhythm Chest X-ray isnormal and a urine drug screening is negative

This patient has had a panic attack Panic attacks can present with a variety ofsymptoms including palpitations, sweating, trembling, sensation of shortness ofbreath or smothering, feeling of choking, chest pain or discomfort, nausea orabdominal distress, derealization or depersonalization, fear of losing control, fear

of dying, paresthesias, and chills or hot flushes The attack must be a period ofintense fear or discomfort with four or more symptoms developing abruptly andreaching a peak within 10 minutes This should be considered in a young,healthy patient with chest pain and otherwise normal findings, particularly whenaccompanied by a precipitating event In this case, the patient’s attack may havebeen triggered by the argument Panic disorder is characterized by recurrentunexpected panic attacks or persistent concern of having a panic attack or itsconsequences This may or may not be accompanied by agoraphobia, a fear ofbeing in public places Panic attacks on exposure to specific situations arecharacterized as a specific phobia It is important to rule out cocaine-inducedmyocardial ischemia, which can be seen on ECG and urine drug panel

A 42-year-old woman is being seen by her primary care physician for an annualvisit Her only complaint is daytime fatigue that has been affecting herperformance at work She denies any fever, weight changes, temperatureintolerance, weakness, or lightheadedness Inquiry into sleep patterns revealsthat she awakens in fear each night due to recurring dreams of being followed,often with palpitations and profuse sweating After further questioning, shetearfully admits that she was sexually assaulted in a parking garage 3 monthsago Further discussion reveals that the patient has debilitating panic attackswhenever she sees a parking garage and now avoids going out in publicwhenever possible

This patient has posttraumatic stress disorder (PTSD) PTSD is characterized bythe exposure to a traumatic event that the person persistently re-experiences.This may be through intrusive thoughts of recollection, recurrent dreams,flashbacks, or intense responses to external cues Patients will also haveincreased arousal and avoidance of stimuli associated with the event The level

of disturbance in PTSD will cause impairment of social, occupational, or otherimportant area of functioning In addition, like any other diagnosis in psychiatry,the condition must not be due to the effect of a substance (e.g., illicit drug,medication), medical condition, or exacerbation of a preexisting axis I(psychiatric) or axis II (personality) disorder PTSD can present with symptomssimilar to generalized anxiety disorder, so a complete history is essential It isimportant to note that in patients with PTSD who have a military background,there is a high incidence of concurrent substance abuse Therefore, it isimportant to screen for alcohol and drug use, and generally, BZDs are notrecommended in this population

A 16-year-old female is brought to the gynecologist by her mother foramenorrhea Her first menses was at 12 years of age, and she developed regularmonthly cycles until about a year ago Her last menses was 6 months ago Thepatient states that she is not sexually active Physical examination reveals aslender female, Tanner Stage V She is 65 inches (165 cm) tall and weighs 104 lb(47.2 kg) with a BMI of 17.1 kg/m2 Pelvic examination is unremarkable Skinexamination shows soft, fine hair on her extremities and a small abrasion of theskin over the right third and fourth metacarpophalangeal joints When askedabout the abrasion, the patient states she scratched her hand during gymnasticspractice

This patient has anorexia nervosa To meet the DSM-IV criteria, a patient must

be less than 85% of ideal body weight, but maintain a distorted impression oftheir body weight or shape, with an intense fear of gaining weight and 3 months

of amenorrhea Since calculating 85% of total body weight can be timeconsuming in the clinical setting, a BMI of less than 17.5 kg/m2 is typically used

as the standard indicating an anorexic weight range Amenorrhea in anorexianervosa is a result of low levels of luteinizing hormone (LH) and suppression ofphysiologic hormone fluctuations Lanugo (thin body hair) is one of manycomplications that can develop from anorexia, which can also includeosteoporosis, cachexia, cardiac arrhythmias, and even sudden death Thispatient’s skin abrasion is suggestive of self-induced vomiting Anorexics mayachieve and maintain their low weight through a number of methods includingbinging, purging (vomiting, laxative abuse, diuretics, etc.), excessive exercise,and starvation Complications of purging can include electrolyte abnormalities(particularly hypokalemia), salivary gland enlargement, dental caries, andseizures Patients with bulimia nervosa also binge and purge; however, they have

a normal or high BMI, without such distortion in body perception Patients mayalso have an isolated distorted perception of a specific part of their body, which

is known as body dysmorphic disorder

A 57-year-old male presents to his primary care physician for follow-up on hishypertension In addition, he notes that he is always tired and frequently fallsasleep at work He reports that he usually goes to bed around 10:30 PM andwakes up at 7:00 AM and does not have problems falling asleep or staying asleep.However, he is still very tired when his alarm clock wakes him up He takeslisinopril and hydrochlorothiazide for hypertension His blood pressure is 158/86

mm Hg, pulse is 74/min, respiratory rate is 14/min, and temperature is 36.9°C(98.4°F) The patient’s BMI is 35 kg/m2 Physical examination shows an obesemale with a mildly erythematous oropharynx, and presence of an S4 heart sound

in addition to S1 and S2

This patient has obstructive sleep apnea (OSA), which is characterized byfunctional obstruction of the upper airway for brief periods while the patientsleeps These pauses (periods of apnea) last at least 10 seconds and often longer,leading to a decrease in arterial oxygen saturation and transient arousal fromsleep Patients are usually not aware of these disturbances while they aresleeping, but will often awake from a sufficient period of sleep without feelingrefreshed and have unexplained excessive daytime sleepiness Typically, apartner will also note that they snore loudly OSA is generally found inindividuals with obesity and is frequently associated with hypertension.Narcolepsy is much less common, but also presents with excessive daytimesleepiness and intrusion of aspects of rapid eye movement (REM) sleep intodaytime wakefulness The most common symptoms are sleep attacks, in which apatient cannot avoid falling asleep, typically leading to irresistible 10- to 20-minute periods of sleep These can occur at very inconvenient times, such aswhile driving, and may include cataplexy, a sudden loss of muscle tone, that maylead to collapse from paralysis of all skeletal muscles Other conditions that canlead to daytime sleepiness include shift work (disruption of circadian rhythms),restless leg syndrome, jet lag, and insufficient sleep

A 33-year-old female presents to the emergency department with acute epigastricpain She describes the pain as sharp, constant, and unbearable It is notassociated with eating and gets worse with moving Review of systems is alsopositive for headache, nausea, dizziness, dyspha-gia, shortness of breath, neckpain, easy bruising, and increased urinary frequency She is afebrile, and othervital signs are normal Examination reveals a soft, nondistended abdomen withnormo-active bowel sounds that is tender to percussion and palpation in allareas There is no guarding or rebound tenderness A review of her recordsshows that she was recently admitted and received a colonoscopy for intractablediarrhea She has also had several visits over the past few years forgastroenteritis, unexplained knee pain, and a urinary tract infection In addition,she underwent exploratory laparoscopy for menometrorrhagia and underwentdiagnostic evaluation for possible multiple sclerosis

This patient has somatization disorder, a very specific diagnosis out of the fivesomatoform disorders It entails a history of multiple physical complaintsbeginning before the age of 30 years and occurring over a period of years witheither treatment or significant impairment in social or occupational functioning.The complaints must include four pain symptoms (related to at least fourdifferent sites or functions), two GI symptoms other than pain (e.g., nausea,vomiting, diarrhea), one sexual or reproductive symptom other than pain (e.g.,sexual dysfunction, irregular menses), and one pseudoneurological symptomother than pain (e.g., impaired coordination, weakness, double vision), none ofwhich can be explained by physical or laboratory examination In this disorder,the symptoms are the result of unconscious psychological factors and are notintentionally produced, such as in factitious disorder, where the patientmotivation is to assume the sick role, or in malingering, where externalincentives such as financial gain are present Related disorders include paindisorder, in which pain at one or more anatomical sites is the predominant focus,and conversion disorder, manifested by one or more neurologic symptomsaffecting voluntary motor or sensory function

A 16-year-old girl presents with concerns about daily headaches and blurredvision She also complains of weight gain and constipation over the past 3months She is fatigued, has a low exercise tolerance, and is feeling stressedkeeping up with school work She has missed her last four periods She is notsexually active Menarche occurred at the age of 12 years Her blood pressure is85/55 mm Hg, pulse is 66/min, respiratory rate is 14/min, and temperature is36.8°C (98.1°F) She is 157 cm (5 ft 2 in) tall and weighs 65 kg (143 lb); BMI is

26 kg/m2 Physical examination reveals a pale girl with cool extremities Thereare scattered dry patches of skin on her torso Her reflexes are hypoactivebilaterally, and her temporal visual fields are decreased Initial laboratory resultsare notable for hyponatremia, hypercholesterolemia, and low TSH A pregnancytest is negative She is referred for further endocrine testing and cranial imaging

A 58-year-old male presents at the emergency room following a motor vehicleaccident He has minor injuries from the accident but reports frequent headachesand blurred vision that have worsened over the past several weeks This is hissecond motor vehicle accident in the past 3 months Blood pressure is 170/110

mm Hg, pulse is 78/min, respiratory rate is 16/min, and temperature is 37.0°C(98.6°F) Physical examination is notable for coarse facial features, large doughyhands, and large, wide feet Laboratory data obtained 3 days later are notable forhyperglycemia and increased insulin-like growth factor-1 (IGF-1) concentration;serum levels of prolactin, TSH, serum electrolytes, liver enzymes, and BUN areall within reference range Cranial imaging indicates a pituitary mass

This patient has acromegaly due to excess growth hormone (GH) secretion Inalmost all cases, excess GH secretion from a pituitary adenoma is the cause.Commonly, there is concomitant secretion of prolactin, and disruption of TSHsecretion, although these confounding problems are not present in this patient.Headache and temporal hemianopia result from the pituitary mass pressing onthe optic chiasm GH promotes somatic growth mainly through its action tostimulate secretion of IGF-1 from the liver and other tissues In young patients,prior to closure of the epiphyseal growth plates, the result is gigantism Inmature individuals there is growth of the skull, facial features, hands, and feetleading to the characteristic appearance of acromegaly Growth of the internalorgans also occurs and cardiomegaly is of particular concern Hypertension is acommon finding in acromegaly but is of uncertain origin Since GH is normally

an anti-insulin hormone that helps to maintain blood glucose concentration inresponse to stressors, patients with GH excess frequently have insulin resistanceand may develop DM, as in this case The treatment of choice is transsphenoidalmicrosurgery to remove the pituitary adenoma and is curative in approximately70% of cases

A 29-year-old woman is concerned about her inability to conceive a pregnancyafter 6 months of unprotected intercourse Previously her menstrual cycles wereregular, but she has missed her last two periods Home pregnancy tests arenegative She is in a monogamous relationship with a 38-year-old male Neitherpartner has previously conceived a child She has no previous history of pelvicinflammatory disease, and both partners deny ever having a sexually transmittedinfection Her partner’s semen analysis is normal for volume, sperm count, andmotility Her physical examination is unremarkable except for a milky dischargefrom the nipples Documentation of ovulation using basal body temperatureindicates no ovulation Serum analysis shows increased prolactin concentration,decreased FSH and LH, and normal TSH levels There is no detectableabnormality on cranial imaging

This patient has secondary amenorrhea due to hyperprolactinemia In this casethe patient has a functioning pituitary microadenoma that is not detectable onMRI Excessive prolactin levels inhibit hypothalamic gonadotropin-releasinghormone (GnRH) secretion, leading to a decrease in FSH and LH secretion Thishas resulted in disruption to the ovarian and menstrual cycles severe enough tocause anovulation and secondary amenorrhea in this patient In males,hyperprolactinemia causes hypogonadotropic hypogonadism, decreased libido,and erectile dysfunction There are many possible causes of hyperprolactinemia,including physiologic causes such as pregnancy, pharmacologic adverse effects(e.g., antipsychotic medications), and pathologic causes (e.g., prolactinoma) Thedominant regulation of prolactin secretion from the anterior pituitary gland is viasuppression of secretion by hypothalamic dopamine Hyperprolactinemia istreated with oral administration of synthetic dopamine agonists (e.g.,cabergoline, bromocriptine); larger secretory tumors are surgically treated

A 48-year-old male complains of continual thirst and polyuria During the day hecontinually craves ice water He was diagnosed with rheumatoid arthritis (RA) 2years ago, which is managed with daily oral corticosteroid medication His bloodpressure is 100/70 mm Hg, pulse is 98/min, respiratory rate is 16/min, andtemperature is 37.0°C (98.6°F) Physical examination is unremarkable.Laboratory data are notable for hypernatremia A 24-hour urine collection has avolume of 8 L, and the urine is of low specific gravity; the urine sediment isbland An intranasal desmopressin challenge test produces a prompt but transientdecrease in thirst and urine production

This patient has central diabetes insipidus (DI) A relative lack of vasopressinsecretion from the posterior pituitary causes a defect in urine concentratingability resulting in passage of large volumes of dilute urine (up to 20 L/d) Tomaintain normal plasma osmolarity, patients must drink a large volume of water

to compensate for urinary water loss If the patient has a defective thirstmechanism or does not have adequate access to drinking water, dehydrationresults and hypernatremia occurs The loss of vasopressin secretion can have aprimary cause (e.g., autoimmune disease) or may result from a secondary causesuch as trauma, infection, or tumor metastasis In central DI, the renal tubulesare normal and able to respond to vasopressin, and patients can be treated with

V2-receptor agonists such as desmopressin In this patient, chronic treatmentwith corticosteroids is a confounding factor because corticosteroid medicationsincrease free water excretion Nephrogenic DI has similar symptoms but iscaused by a relative lack of renal response to vasopressin, which continues to benormally secreted by the pituitary gland Nephrogenic DI may be congenital oracquired (e.g., pyelonephritis, renal amyloidosis, potassium depletion, lithiumtreatment) Nephrogenic DI cannot be treated with vasopressin analogues

A 38-year-old woman is distressed about her general appearance due to weightgain and the poor condition of her skin and hair She also describes fatigue, coldintolerance, and constipation that have become worse over the past 3 to 4months Her blood pressure is 130/100 mm Hg, pulse is 52/min, respiratory rate

is 10/min, and temperature is 35.8°C (96.4°F) Physical examination showsbrittle hair, nails, and skin Her face has a puffy appearance Her thyroid gland isdiffusely enlarged She has peripheral edema and her deep tendon reflexes showdelayed relaxation Laboratory findings are notable for hyponatremia, andincreased serum LDL cholesterol and triglycerides The serum TSH level isincreased and titers of antibodies against thyroglobulin and thyroperoxidase arehigh

This patient has hypothyroidism Deficiency of active thyroid hormones (T3 and

T4) has widespread consequences that include decreased metabolic rate,commonly manifesting as weight gain, fatigue, and cold intolerance Thyroidhormones are needed for normal beta-adrenergic system function; bradycardia isdue to decreased beta-adrenergic tone Diastolic hypertension is also frequentlypresent due to isolated alpha-adrenergic vasoconstriction without concomitantbeta-adrenergic receptor activation Renal dysfunction is responsible for fluidretention and hyponatremia Thyroid hormone deficiency decreases nervoussystem function, with reduced mentation and depressed reflexes This patient hasmyxedema from chronic hypothyroidism, in which there is accumulation ofmucopolysaccharides in interstitial tissues, contributing to peripheral edema and

a puffy appearance to the skin Elevated TSH levels result from a lack ofnegative feedback from active thyroid hormone, and this indicates that thepatient has primary hypothyroidism High TSH causes hypertrophy of thethyroid gland itself and subsequent goiter formation Based on antibody titers,this patient has Hashimoto’s thyroiditis, an autoimmune condition that is themost common cause of hypothyroidism in the United States Other causes ofhypothyroidism include dietary iodine deficiency and gland destruction fromradiation, surgery, or chemotherapy Rarely, hypothyroidism has a secondarycause from lack of hypothalamic/pituitary stimulation, in which case TSH levelsare low and no goiter is observed

A 28-year-old female presents with feelings of anxiety and restlessness She hasrecently lost 20 lb and has several loose bowel movements daily She reportspalpitations and muscle weakness when exercising In the last 3 months herperiods have been irregular Her blood pressure is 148/90 mm Hg, pulse is104/min, respiratory rate is 18/min, and temperature is 38.2°C (100.8°F) Onphysical examination she is diaphoretic and the skin is warm to the touch Herheart beat is forceful and irregular Reflexes are brisk, and there is a visibletremor in both hands Her gaze has a staring quality There is diffuseenlargement of the thyroid gland, and a bruit can be heard over it uponauscultation Laboratory data are notable for decreased serum TSH andincreased free T4 Titers of antithyroglobulin and antimicrosomal antibody areelevated and thyroid-stimulating immunoglobulins (TSI) are detected

This patient has hyperthyroidism (thyrotoxicosis) High levels of thyroidhormones cause widespread disruption with increased metabolic rate oftenleading to weight loss and heat intolerance Overactivity of the beta-adrenergicsystem results in cardiovascular effects such as tachycardia, arrhythmias, andhypertension This patient has Graves’ disease, the most common cause ofhyperthyroidism, resulting from the production of TSI These autoantibodies act

as agonists at the TSH receptor and drives excess secretion of thyroid hormones.There is also growth of the gland and increased vascularization (note the bruitheard over the gland) TSH levels are suppressed by negative feedback fromexcessive thyroid hormones Graves’ ophthalmopathy occurs in approximatelyone-third of patients due to cross-reactivity between TSI and periorbital tissues.Other causes of hyperthyroidism include toxic adenomas of the thyroid andiodine-containing medications such as the anti-arrhythmic drug amiodarone.Secondary hyperthyroidism due to a TSH-secreting tumor is a rare condition.Treatment of Graves’ disease includes thiourea drugs to inhibit the enzymethyroid peroxidase and thereby decrease thyroid hormone synthesis Ablation ofthe gland using radioactive iodine or surgery may also be indicated

A 44-year-old male presents with tingling of the lips and hands He alsocomplains of intermittent spasms in his hands and feet and abdominal cramps.Two weeks ago he underwent surgery to remove thyroid cancer and until nowhis recovery has been uneventful His blood pressure is 122/84 mm Hg, pulse is80/min, respiratory rate is 18/min, and temperature is 37.8°C (100.0°F) Onphysical examination there is facial muscle contraction after tapping on thefacial nerve in front of the ear (positive Chvostek’s sign) Laboratory data arenotable for decreased serum-free calcium and increased phosphateconcentration Serum albumin and alkaline phosphate levels are within referencerange The results of hormone assays are pending

This patient has hypoparathyroidism This can be congenital or caused byautoimmune disease but in this case is acquired as the result of thyroid surgery.Loss of PTH causes the inability to maintain normal serum calcium (and to alesser extent magnesium) levels, resulting in hypocalcemia PTH normally acts

to increase serum calcium by increasing bone turnover, decreasing renal calciumexcretion, and by stimulating the renal synthesis of 1,25-dihydroxycholecalciferol (vitamin D3), which in turn increases intestinal calciumabsorption The tingling sensation and muscle cramps reflect increasedexcitability of nerve and muscle due to hypocalcemia Low serum calciumaffects the gating of voltage-sensitive sodium channels and results inhyperexcitability of the cell membrane potential This is demonstrated with apositive Chvostek’s sign or by the Trousseau phenomenon in which inflation of asphygmomanometer cuff induces tetany in muscles distal to the cuff Otheractions of PTH include maintaining renal phosphate excretion by suppressingproximal tubular phosphate reabsorption The loss of PTH therefore also leads tohyperphosphatemia Similar clinical findings are seen in rare patients with PTHresistance (“pseudohypoparathyroidism”) that arises from mutations in the PTHreceptor or associated G-protein coupling In most cases patients withhypoparathyroidism can be treated with a vitamin D supplement to increaseserum calcium concentration

A 67-year-old woman presents with severe flank pain on her left side On furtherquestioning she reports polyuria, polydipsia, frequent abdominal discomfort, andconstipation She has experienced wrist pain bilaterally that has been gettingworse for several weeks She describes feeling depressed about her general state

of health and has not been sleeping well for several months Her blood pressure

is 152/96 mm Hg, pulse is 50/min, respiratory rate is 12/min, and temperature is36.8°C (98.1°F) Physical examination is notable for tenderness in the leftcostovertebral angle and for diminished deep tendon reflexes No neck massesare detected ECG findings include a prolonged PR interval Laboratory findingsare remarkable for increased serum total calcium concentration and reducedserum phosphate; BUN, creatinine, and alkaline phosphatase levels are normal.Serum PTH levels are increased Urinary calcium and phosphate excretion isincreased

of calcium also leads to increased renal filtration of calcium that overwhelmstubular reabsorptive capacity and causes hypercalciuria Suppression of renalphosphate reabsorption by PTH accounts for increased urinary phosphate andsubsequent low serum phosphate Hypercalcemia leads to depressed activity ofexcitable tissues, accounting for bradycardia, first-degree heart block (in thiscase), depressed reflexes, CNS symptoms, and reduced GI motility.Hypercalcemia also inhibits the action of vasopressin at the kidney causingnephrogenic DI Mild cases are treated with high fluid intake and dietarycalcium restriction; surgical removal of one or more parathyroid glands isundertaken in selected cases.

A 78-year-old man presents with a hip fracture due to a fall He describes muscleweakness and bone pain over the past year Past medical history is notable forskin cancer 10 years ago, and he is now careful to avoid sun exposure He takes

no medications and has not visited a physician in the past 3 years His bloodpressure is 140/80 mm Hg, pulse is 70/min, respiratory rate is 12/min, andtemperature is 36.2°C (97.2°F) He is 175 cm (5 ft 9 in) tall and weighs 54 kg(120 lb); BMI is 17.7 On physical examination the patient is pale and appearsmalnourished with low muscle mass Radiographs indicate a fracture of the neck

of the femur There are other bands of decreased bone density giving the falseappearance of small fractures (pseudofractures) Laboratory data are notable fordecreased serum calcium, phosphate, and vitamin D levels Serum alkalinephosphate is increased, but renal and liver function tests are within referenceranges

This patient has osteomalacia resulting from vitamin D deficiency In metabolicbone disease there is decreased bone density and reduced bone strength Inosteomalacia the defect is limited to loss of bone mineralization, whereas inosteoporosis there is also loss of the collagenous bone matrix Vitamin D isrequired for normal mineralization of bone by osteoblasts with calciumphosphate (hydroxyapatite) crystals Inadequate vitamin D in children causes theirreversible bone deformities of rickets, and in adults it causes osteomalacia.Vitamin D is synthesized in the skin following exposure to UV-B light and isalso available in the diet Activation of vitamin D requires 25-hydroxylation inthe liver and final conversion to 1,25-(OH)2 D3 (cholecalciferol) in the kidney,under the control of PTH This patient is at high risk for vitamin D deficiencydue to his very restricted diet and avoidance of sunlight Vitamin D is requiredfor normal intestinal uptake of calcium and phosphate Vitamin D deficiency inthis patient accounts for low serum calcium and phosphate concentration.Pseudofractures are anomalies seen on radiographs where the periosteumthickens as a healing reaction to an adjacent area of bone demineralization.There are other possible causes of osteomalacia One example is a mesenchymaltumor type, which releases phosphaturic factors such as fibroblast growth factor-

23 (FGF-23), leading to phosphate deficiency and bone disease In childrengenetic forms of rickets can result from mutations in either the 1-alphahydroxylase enzyme for vitamin D activation (rickets type 1), or in the vitamin

D receptor (rickets type 2)

A 38-year-old female presents with muscle weakness, fatigue, and depression.She has lost 20 lb over the past 6 months and has frequent nausea She feelslightheaded before meals and when she stands up too quickly She has decreasedlibido and is concerned about the loss of pubic hair Her blood pressure is 96/68

mm Hg, pulse is 88/min, respiratory rate is 14/min, and temperature is 36.5°C(97.7°F) Blood pressure falls more than 20 mm Hg upon standing (orthostasis).She is 160 cm (5 ft 3 in) tall and weighs 50 kg (110 lb); BMI is 19.5 Onphysical examination there is increased skin pigmentation of the palmar creases,knuckles, and elbows There is scant pubic and axillary hair Peripheral pulsesare 1 + (decreased in amplitude) bilaterally Laboratory data show hyponatremia,hyperkalemia, and fasting hypoglycemia An 8:00 AM serum cortisol level isdecreased and serum ACTH level is increased