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Question 21Question →

Match each clinical scenario describing a medication adverse effect or monitoring requirement in a patient with a rheumatologic condition to the most likely responsible pharmacologic agent.

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Items

A 55-year-old woman with rheumatoid arthritis develops sudden, severe abdominal pain. Imaging reveals free intraperitoneal air indicating bowel perforation. She recently started a new biologic disease-modifying antirheumatic drug.
A 32-year-old woman with severe lupus nephritis presents with painless gross hematuria. She has been receiving monthly intravenous infusions for her lupus. Cystoscopy reveals a bladder neoplasm.
A 45-year-old man with ankylosing spondylitis develops a new-onset photosensitive malar rash, pleuritis, and positive anti-histone antibodies six months after starting a biologic therapy.
A 29-year-old woman with rheumatoid arthritis desires pregnancy. She is currently taking a non-biologic DMARD that requires an accelerated elimination procedure with cholestyramine prior to conception.
A 38-year-old woman with systemic lupus erythematosus presents for her annual ophthalmologic screening, which includes spectral-domain optical coherence tomography to evaluate for maculopathy.

Matches

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Answer

The scenarios match with Tocilizumab (bowel perforation), Cyclophosphamide (bladder neoplasm), Infliximab (drug-induced lupus), Leflunomide (cholestyramine washout), and Hydroxychloroquine (maculopathy screening).
Each rheumatologic medication carries a distinct side effect and monitoring profile. Tocilizumab (IL-6 inhibitor) increases the risk of bowel perforation. Cyclophosphamide causes urothelial toxicity (hemorrhagic cystitis, bladder cancer) via its metabolite acrolein. Infliximab (TNF-alpha inhibitor) is classically associated with drug-induced lupus. Leflunomide is teratogenic and undergoes enterohepatic circulation, requiring cholestyramine for rapid clearance. Hydroxychloroquine causes retinal toxicity requiring rigorous OCT or visual field screening.

Step-by-Step Solution

1
Analyze the first scenario featuring bowel perforation on a biologic.
Identify Tocilizumab (IL-6 inhibitor) as the most likely causative agent.
IL-6 inhibition is uniquely associated with lower gastrointestinal perforation compared to other biologics.
2
Analyze the second scenario featuring a bladder neoplasm after IV infusions for lupus.
Identify Cyclophosphamide as the causative agent.
Cyclophosphamide metabolism produces acrolein, which is highly toxic to the urothelium and oncogenic.
3
Analyze the third scenario featuring drug-induced lupus on a biologic.
Identify Infliximab (TNF-alpha inhibitor) as the causative agent.
Anti-TNF agents are the most common biologics implicated in drug-induced lupus.
4
Analyze the fourth scenario featuring a teratogenic DMARD requiring cholestyramine washout.
Identify Leflunomide as the responsible agent.
Leflunomide undergoes extensive enterohepatic circulation, and cholestyramine binds the drug in the gut to accelerate its elimination.
5
Analyze the fifth scenario featuring regular OCT screening for maculopathy.
Identify Hydroxychloroquine as the responsible agent.
Hydroxychloroquine binds to melanin in the retinal pigment epithelium, leading to dose-dependent, irreversible retinal toxicity.

Key Concept

Adverse effects and screening requirements of rheumatologic pharmacotherapy
Question 22Question →

Match each pediatric clinical presentation to its most likely underlying enzymatic deficiency.

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Items

A 2-week-old 46,XX infant presents with clitoromegaly, partial labial fusion, serum sodium of 122 mEq/L, and serum potassium of 6.5 mEq/L.
A 2-week-old 46,XX infant presents with ambiguous genitalia, a blood pressure >95th percentile for age, and a serum potassium of 2.8 mEq/L.
A 15-year-old phenotypic female presents with primary amenorrhea, absent secondary sexual characteristics, a blood pressure of 145/95 mmHg, and a 46,XY karyotype.
A 2-week-old 46,XX infant presents with ambiguous genitalia, normal blood pressure, and normal electrolytes, accompanied by a maternal history of severe facial hair growth and voice deepening during the pregnancy.

Matches

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Answer

The correct matches correlate 21-hydroxylase deficiency with salt-wasting CAH, 11β-hydroxylase deficiency with hypertensive virilizing CAH, 17α-hydroxylase deficiency with hypertensive sexual infantilism, and placental aromatase deficiency with virilization alongside normal electrolytes.
Each disorder presents with a unique constellation of mineralocorticoid, glucocorticoid, and sex hormone derangements depending on the specific location of the enzymatic block in the steroidogenesis pathway.

Step-by-Step Solution

1
Evaluate the electrolyte and blood pressure profile to determine the presence of mineralocorticoid excess or deficiency.
Hyponatremia and hyperkalemia indicate mineralocorticoid deficiency. Hypertension and hypokalemia indicate mineralocorticoid excess.
This establishes whether the block in the steroidogenesis pathway occurs before or after the synthesis of mineralocorticoid precursors.
2
Assess the phenotypic sex and karyotype against the degree of virilization.
Virilized 46,XX infants have excess androgens, whereas a 46,XY patient appearing as a phenotypic female has deficient androgens.
This identifies if the enzymatic block prevents sex hormone synthesis (as in 17α-hydroxylase deficiency) or shunts precursors toward it (as in 21- and 11β-hydroxylase deficiencies).
3
Incorporate maternal history for isolated virilization cases with normal adrenal function.
Maternal virilization combined with a virilized 46,XX infant points to a placental block rather than an adrenal defect.
Aromatase is required in the placenta to clear fetal androgens by converting them to estrogens; without it, androgens accumulate and virilize both the fetus and the mother.

Key Concept

Steroidogenesis pathway enzyme deficiencies and their corresponding clinical presentations
Question 23Question →

Match each clinical vignette describing a characteristic gynecologic neoplasm with the serum tumor marker most likely to be elevated in that patient.

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Items

A 15-year-old girl with a rapidly growing ovarian germ cell tumor that histologically reveals Schiller-Duval bodies.
A 28-year-old woman with hemoptysis, multiple lung nodules, and a recent history of a hydatidiform mole evacuation.
A 20-year-old woman with a solid ovarian tumor composed of uniform cells with clear cytoplasm, resembling a male testicular seminoma.
A 60-year-old woman presenting with postmenopausal bleeding, endometrial hyperplasia, and a unilateral adnexal mass.

Matches

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Answer

The correct matching aligns the yolk sac tumor vignette with AFP, the choriocarcinoma vignette with beta-hCG, the dysgerminoma vignette with LDH, and the granulosa cell tumor vignette with inhibin.
Gynecologic neoplasms have specific histological characteristics, clinical presentations, and secretory profiles. Yolk sac tumors produce alpha-fetoprotein (AFP). Choriocarcinomas are trophoblastic and produce large amounts of beta-hCG. Dysgerminomas are associated with elevated lactate dehydrogenase (LDH). Granulosa cell tumors secrete estrogen and inhibin, making inhibin a highly useful diagnostic marker.

Step-by-Step Solution

1
Analyze the first vignette to identify the underlying neoplasm.
The presence of Schiller-Duval bodies indicates a yolk sac (endodermal sinus) tumor.
Histological findings are highly specific for differentiating ovarian germ cell tumors.
2
Analyze the second vignette to identify the underlying neoplasm.
A recent hydatidiform mole followed by lung metastases describes choriocarcinoma.
Choriocarcinomas often arise from previous molar pregnancies and hematogenously spread to the lungs.
3
Analyze the third vignette to identify the underlying neoplasm.
A tumor resembling a male seminoma in a young woman is a dysgerminoma.
Dysgerminomas are the most common malignant germ cell tumors of the ovary and share histology with seminomas.
4
Analyze the fourth vignette to identify the underlying neoplasm.
Postmenopausal bleeding, endometrial hyperplasia, and an adnexal mass indicate a granulosa cell tumor.
Granulosa cell tumors secrete estrogen, causing endometrial proliferation, and present with concurrent adnexal masses.
5
Match each identified neoplasm with its characteristic serum tumor marker.
Yolk sac tumor pairs with AFP, choriocarcinoma pairs with beta-hCG, dysgerminoma pairs with LDH, and granulosa cell tumor pairs with inhibin.
These are the established biochemical markers for diagnosing and monitoring these specific gynecologic tumors.

Key Concept

Diagnostic tumor markers in gynecologic neoplasms
Question 24Question →

Correlate each of the following clinical encounters or professional scenarios with the legally or ethically mandated next step regarding disclosure.

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Items

A toddler displaying symmetric lower extremity scald injuries that the guardian attributes to an accidental slip into a hot shower.
An octogenarian whose live-in relative refuses to allow private clinical interviews and is actively diverting the patient's retirement funds.
An attending interventionalist who smells strongly of ethanol and exhibits motor tremors immediately prior to a scheduled angiogram.
A married, competent young adult requesting an elective medical pregnancy termination while demanding absolute secrecy from their spouse.
A sexually active adult whose nucleic acid amplification test confirms an active infection with Neisseria gonorrhoeae.

Matches

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Answer

The toddler with burns maps to Child Protective Services. The exploited octogenarian maps to Adult Protective Services. The impaired interventionalist maps to the Physician Health Program. The abortion request maps to maintaining confidentiality. The Neisseria gonorrhoeae infection maps to the Department of Public Health.
Each scenario represents a distinct legal or ethical pillar of medical practice. Child Protective Services and Adult Protective Services are designated for vulnerable populations suffering abuse. The Physician Health Program manages professional impairment to protect the public. The Department of Public Health handles communicable diseases. Conversely, a competent adult seeking an abortion does not fall under any reporting exception, making confidentiality the only correct action.

Step-by-Step Solution

1
Analyze the pediatric scenario (toddler with burns).
Identify suspicion of child abuse due to an incompatible mechanism of injury.
Stocking-glove pattern immersion burns require immediate mandatory reporting to CPS.
2
Analyze the geriatric scenario (diverted funds).
Identify financial and potential emotional elder abuse.
Vulnerable adults and elders require mandated reporting to APS when exploitation is suspected.
3
Analyze the professional scenario (intoxicated attending).
Identify a medically impaired colleague posing imminent patient harm.
Ethical and legal guidelines mandate reporting impaired colleagues to supervisory clinical entities or a state-approved PHP.
4
Analyze the reproductive health scenario (abortion request).
Recognize a competent adult exercising medical autonomy.
There is no mandatory reporting to spouses; breaking HIPAA here is a legal violation.
5
Analyze the infectious disease scenario (gonorrhea).
Identify a reportable sexually transmitted disease.
Public health law requires clinicians to report specific communicable diseases to the DPH.

Key Concept

Physicians must balance standard patient confidentiality with specific statutory mandates requiring the disclosure of suspected child or elder abuse, certain communicable diseases, and impaired colleagues.
Question 25Question →

Match each post-bariatric surgery clinical presentation with its most appropriate diagnostic or therapeutic next step.

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Items

A 42-year-old woman experiences crampy abdominal pain, diaphoresis, and palpitations 30 minutes after eating, 6 months following a Roux-en-Y gastric bypass.
A 35-year-old man presents with severe, colicky abdominal pain and nausea 2 years after a Roux-en-Y gastric bypass; CT abdomen shows a mesenteric swirl sign.
A 48-year-old woman who recently resumed smoking reports burning epigastric pain that worsens with fasting, 1 year after a Roux-en-Y gastric bypass.
A 39-year-old man develops sustained tachycardia of 130/min, fever, and left shoulder pain on postoperative day 2 following a Roux-en-Y gastric bypass.

Matches

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Answer

Dumping syndrome requires dietary modification; internal hernias require prompt surgical exploration; marginal ulcers require endoscopy and proton pump inhibitors; and anastomotic leaks require urgent water-soluble contrast imaging or reoperation.
Bariatric surgery, specifically Roux-en-Y gastric bypass, alters normal gastrointestinal anatomy and physiology, leading to unique complications that mandate specific interventions. Early complications like anastomotic leaks manifest primarily as unexplained tachycardia and peritonitis, requiring urgent imaging or exploration. Late complications include dumping syndrome (managed conservatively with diet), marginal ulcers (managed medically after endoscopic confirmation), and internal hernias (requiring definitive surgical closure to prevent ischemia). Aligning the pathophysiology with the correct intervention is critical for surgical triage.

Step-by-Step Solution

1
Analyze the timing and nature of symptoms for the first presentation.
Postprandial vasomotor and gastrointestinal symptoms at 6 months indicate early dumping syndrome.
Rapid transit of hyperosmolar food boluses draws fluid into the intestine and triggers autonomic reflexes; this is best managed with dietary changes.
2
Evaluate the radiographic findings and timeline for the second presentation.
A mesenteric swirl sign on CT years after surgery points to an internal hernia.
Roux-en-Y gastric bypass creates mesenteric defects that allow bowel herniation and strangulation, requiring prompt surgical intervention.
3
Identify the risk factors and symptom pattern in the third presentation.
A smoker experiencing fasting epigastric pain at 1 year is highly suspicious for a marginal ulcer.
The gastrojejunal anastomosis is vulnerable to ulceration from poor mucosal perfusion, NSAIDs, or smoking, warranting endoscopic evaluation and acid suppression.
4
Assess the acute vital sign abnormalities in the fourth presentation.
Unexplained early postoperative tachycardia and signs of peritonitis suggest an anastomotic leak.
Leaks are life-threatening early complications that demand immediate identification with water-soluble contrast or urgent surgical exploration.

Key Concept

Diagnosis and management of common early and late complications of Roux-en-Y gastric bypass.
Question 26Question →

Match each clinical presentation and characteristic physical examination finding with the most likely underlying valvular pathology.

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Items

A 24-year-old woman with a mid-systolic click followed by a late systolic murmur that becomes longer and louder with the Valsalva maneuver.
A 68-year-old man with syncope, a delayed carotid upstroke, and a harsh crescendo-decrescendo systolic murmur at the right upper sternal border.
A 45-year-old man with a bounding pulse, head bobbing, and a high-pitched, blowing early diastolic decrescendo murmur at the left sternal border.
A 32-year-old woman with hemoptysis, a loud first heart sound (S1), and a low-pitched mid-diastolic rumbling murmur at the cardiac apex.

Matches

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Answer

The mid-systolic click with Valsalva accentuation matches mitral valve prolapse; the delayed carotid upstroke with a harsh systolic murmur matches aortic valve stenosis; the bounding pulse with an early diastolic murmur matches aortic valve regurgitation; and the loud S1 with a mid-diastolic rumble matches mitral valve stenosis.
Each clinical vignette presents a pathognomonic set of physical exam findings for a specific valvular lesion. A mid-systolic click with a late systolic murmur that worsens with decreased preload points to mitral valve prolapse. A delayed carotid upstroke with a harsh right-sided systolic murmur indicates aortic valve stenosis. Bounding pulses with an early diastolic murmur reveal aortic valve regurgitation. A loud S1 with a mid-diastolic rumbling murmur is characteristic of mitral valve stenosis.

Step-by-Step Solution

1
Analyze the young woman's presentation of a click and late systolic murmur.
Identified the murmur as mitral valve prolapse.
Valsalva decreases preload, which worsens the prolapse of redundant mitral valve leaflets, causing the murmur to appear earlier and become louder.
2
Analyze the elderly man's presentation of syncope and delayed carotid upstroke.
Identified the murmur as aortic valve stenosis.
The classic triad of symptoms (syncope, angina, dyspnea) along with pulsus parvus et tardus indicates fixed left ventricular outflow tract obstruction.
3
Analyze the middle-aged man's presentation of bounding pulses and head bobbing.
Identified the murmur as aortic valve regurgitation.
These peripheral signs indicate a hyperdynamic circulation and widened pulse pressure resulting from the rapid runoff of blood back into the left ventricle during diastole.
4
Analyze the young woman's presentation of hemoptysis and a diastolic rumble.
Identified the murmur as mitral valve stenosis.
This auscultatory profile, combined with signs of elevated pulmonary venous pressure (hemoptysis), strongly points to an obstructed mitral orifice, often rheumatic in origin.

Key Concept

Valvular Heart Disease Physical Examination Findings
Question 27Question →

Match each patient's clinical presentation and laboratory profile to the most likely underlying pathophysiologic mechanism.

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Items

A 68-year-old man with a long smoking history presents with confusion and a central lung mass. Laboratory studies show serum calcium 13.5 mg/dL, phosphorus 2.1 mg/dL, and intact PTH 9 pg/mL (normal 15-65 pg/mL).
A 45-year-old woman is evaluated for a history of recurrent renal colic. Laboratory studies show serum calcium 11.2 mg/dL, phosphorus 2.4 mg/dL, and intact PTH 88 pg/mL.
A 24-year-old man is found to have asymptomatic hypercalcemia on routine insurance screening. Laboratory studies show serum calcium 11.4 mg/dL, intact PTH 42 pg/mL, and 24-hour urine calcium of 35 mg/day.
A 32-year-old African American woman presents with persistent dry cough, erythema nodosum, and bilateral facial nerve palsy. Laboratory studies show serum calcium 11.9 mg/dL, phosphorus 4.4 mg/dL, and intact PTH 12 pg/mL.
A 60-year-old housebound woman presents with diffuse, dull bone pain and proximal muscle weakness. Laboratory studies show serum calcium 7.8 mg/dL, phosphorus 2.2 mg/dL, intact PTH 145 pg/mL, and elevated alkaline phosphatase.

Matches

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Answer

The clinical vignettes represent distinct mechanisms of calcium and phosphorus dysregulation: Humoral hypercalcemia of malignancy (PTHrP), Primary hyperparathyroidism (PTH overproduction), Familial hypocalciuric hypercalcemia (calcium-sensing receptor mutation), Sarcoidosis (ectopic 1-alpha-hydroxylase), and Osteomalacia (Vitamin D deficiency).
Correct matching requires evaluating serum calcium alongside serum phosphorus, intact PTH levels, and key clinical contextual clues to determine whether the metabolic abnormality is PTH-driven, PTH-independent, or a result of a defective receptor set-point.

Step-by-Step Solution

1
Analyze patient 1's profile
High calcium, low phosphorus, low PTH, central lung mass.
Identifies PTH-independent hypercalcemia due to malignancy (PTHrP secretion mimicking PTH effects).
2
Analyze patient 2's profile
High calcium, low phosphorus, high PTH, kidney stones.
Identifies PTH-dependent hypercalcemia caused by primary hyperparathyroidism.
3
Analyze patient 3's profile
High calcium, normal PTH, highly restricted urine calcium.
Identifies an altered calcium sensing set point indicative of Familial Hypocalciuric Hypercalcemia (FHH).
4
Analyze patient 4's profile
High calcium, high-normal phosphorus, low PTH, signs of sarcoidosis.
Identifies 1,25-dihydroxyvitamin D-mediated hypercalcemia from granulomatous macrophage activity.
5
Analyze patient 5's profile
Low calcium, low phosphorus, very high PTH, high alkaline phosphatase.
Identifies secondary hyperparathyroidism in response to severe Vitamin D deficiency causing osteomalacia.

Key Concept

Differential diagnosis of calcium and bone metabolism disorders using paired serum calcium, phosphorus, and parathyroid hormone levels.
Question 28Question →

Match each patient presenting with severe hypertension and distinct clinical features to the most appropriate initial targeted pharmacologic intervention.

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Items

A 65-year-old man presenting with sudden-onset, severe, tearing chest pain radiating to the interscapular region, accompanied by asymmetric pulses in the upper extremities.
A 48-year-old woman with diffuse cutaneous systemic sclerosis who develops sudden oliguric acute kidney injury, microangiopathic hemolytic anemia, and a blood pressure of 230/120 mm Hg.
A 35-year-old man with a known adrenal mass who presents with paroxysmal severe hypertension, pounding headaches, diaphoresis, and tachycardia.
A 72-year-old man with a history of heart failure with preserved ejection fraction presenting with acute severe dyspnea, hypoxia, and diffuse bilateral pulmonary crackles in the setting of a blood pressure of 210/115 mm Hg.

Matches

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Answer

Aortic dissection requires beta-blockade; Scleroderma renal crisis requires ACE inhibition; Pheochromocytoma requires alpha-blockade; Flash pulmonary edema requires venodilation and diuresis.
Each specific hypertensive emergency demands a precise pharmacological mechanism of action to counteract its pathophysiology. Using a generic approach for blood pressure lowering without addressing the specific underlying driver can lead to severe adverse outcomes.

Step-by-Step Solution

1
Analyze the clinical features of each patient to establish the underlying diagnosis causing the hypertensive emergency.
Identified diagnoses are acute aortic dissection, scleroderma renal crisis, pheochromocytoma crisis, and acute decompensated heart failure (flash pulmonary edema).
Accurate diagnosis is required because standard hypertensive emergency protocols vary drastically based on the target organ damage.
2
Identify the primary pathophysiological driver for each condition.
Drivers: shear stress (dissection), RAAS activation (scleroderma), catecholamine surge (pheochromocytoma), and high preload/afterload (flash pulmonary edema).
Understanding the mechanism allows for targeted pharmacotherapy rather than generic blood pressure reduction.
3
Match the diagnosis to the pharmacologic agent that specifically targets that pathophysiologic mechanism.
Matched esmolol to dissection, captopril to scleroderma, phentolamine to pheochromocytoma, and nitroglycerin/diuretics to heart failure.
This pairs the optimal intervention with the specific life-threatening condition while avoiding harmful contraindications.

Key Concept

Targeted pharmacotherapy for specific hypertensive emergencies based on underlying pathophysiology.
Estimated Time:1m 30s
Question 29Question →

Correlate each distinct clinical vignette describing a cardiovascular emergency or structural abnormality with its exact pathophysiological mechanism or primary hemodynamic derangement.

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Items

A 22-year-old athlete experiences exertional presyncope. Cardiac auscultation reveals a harsh crescendo-decrescendo systolic murmur at the lower left sternal border that intensifies during the strain phase of the Valsalva maneuver and softens with a passive leg raise.
A 55-year-old male with a history of Hodgkin lymphoma treated with mediastinal radiation presents with severe peripheral edema and ascites. Jugular venous evaluation shows a prominent y-descent that paradoxically deepens during inspiration.
A 68-year-old male, four days post-inferior wall myocardial infarction, rapidly deteriorates into cardiogenic shock. Auscultation demonstrates a newly developed, harsh holosystolic murmur at the apex radiating to the axilla with an accompanying S3 gallop.
A 29-year-old pregnant female develops sudden hemoptysis and dyspnea. Exam shows a prominent S1, an early diastolic extra sound closely following S2, and a low-pitched apical rumble.

Matches

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Answer

The correct correlations are: The athlete with the Valsalva-responsive murmur matches with dynamic LVOT obstruction (HOCM). The irradiated patient with Kussmaul sign matches with rigid pericardium and ventricular interdependence (Constrictive Pericarditis). The post-MI shock patient matches with papillary muscle rupture and giant v-waves. The pregnant patient with hemoptysis matches with commissural fusion and trans-valvular pressure gradient (Mitral Stenosis).
Each clinical vignette provides highly specific diagnostic clues that uniquely map to a distinct pathophysiologic mechanism. The athlete's murmur is classic for HOCM, driven by SAM of the mitral valve. The radiation survivor exhibits constrictive pericarditis, characterized by a rigid pericardium. The post-MI patient has suffered a papillary muscle rupture causing acute MR and giant v-waves. The pregnant patient's findings are pathognomonic for rheumatic mitral stenosis caused by commissural fusion.

Step-by-Step Solution

1
Analyze the first vignette featuring a murmur that worsens with decreased preload (Valsalva).
Identified as Hypertrophic Obstructive Cardiomyopathy.
Decreasing preload narrows the LV outflow tract, worsening the dynamic obstruction.
2
Evaluate the second presentation involving remote radiation, ascites, Kussmaul sign, and a prominent y-descent.
Diagnosed as Constrictive Pericarditis.
Radiation causes pericardial scarring, leading to restricted filling and dissociation of intracardiac and intrathoracic pressures.
3
Assess the post-MI patient with a new holosystolic murmur, S3 gallop, and cardiogenic shock.
Identified as Acute Mitral Regurgitation secondary to papillary muscle rupture.
The posteromedial papillary muscle frequently ruptures 3-5 days after an inferior MI, causing massive retrograde flow and acute left atrial overload.
4
Examine the pregnant patient with hemoptysis, loud S1, and diastolic rumble.
Diagnosed as Rheumatic Mitral Stenosis.
Pregnancy increases cardiac output, exacerbating the pressure gradient across the fused commissures.

Key Concept

Differentiating structural and valvular cardiac pathologies based on specific hemodynamic responses, unique physical exam findings, and pathophysiologic mechanisms.
Question 30Question →

Evaluate the following clinical vignettes detailing neonates with suspected congenital infections. Match each clinical presentation to the most likely etiologic agent based on the distinctive physical and radiographic findings.

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Items

A 38-week gestation neonate exhibits hepatosplenomegaly, jaundice, and scattered petechiae. Cranial ultrasound reveals calcifications restricted strictly to the subependymal and periventricular zones. The infant fails the evoked otoacoustic emissions test bilaterally.
A 39-week gestation neonate presents with a rapidly increasing head circumference and bulging fontanelles. Neuroimaging displays prominent ventriculomegaly with scattered parenchymal calcifications extending throughout the cerebral cortex. Dilated funduscopic examination shows yellow-white chorioretinal lesions with pigmented margins.
A 37-week gestation neonate develops profound rhinorrhea containing serosanguineous fluid. Skin examination shows vesiculobullous lesions that desquamate, predominantly on the palmar and plantar surfaces. Long bone radiography demonstrates bilateral metaphyseal lucencies.
A 36-week gestation neonate presents with a purpuric rash and hepatosplenomegaly. Physical examination reveals an absent red reflex bilaterally and a continuous, high-pitched machine-like murmur at the left infraclavicular region. Newborn hearing screening is abnormal.

Matches

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Answer

The presentations match as follows: Periventricular calcifications with Cytomegalovirus; Diffuse cortical calcifications and hydrocephalus with Toxoplasma gondii; Desquamating palmar rash and snuffles with Treponema pallidum; and Cataracts with a continuous murmur with Rubella virus.
Each congenital infection presents with a distinct, defining constellation of clinical and radiographic findings. Congenital CMV is distinguished by periventricular calcifications; Toxoplasmosis by diffuse cortical calcifications and severe hydrocephalus; Syphilis by snuffles, palmar/plantar desquamation, and metaphyseal osteochondritis; and Rubella by cataracts and a patent ductus arteriosus.

Step-by-Step Solution

1
Analyze the pattern of intracranial calcifications in the neuroimaging vignettes.
Subependymal/periventricular calcifications isolate Cytomegalovirus, whereas diffuse parenchymal/cortical calcifications with hydrocephalus isolate Toxoplasma gondii.
CMV has a predilection for the germinal matrix lining the ventricles, while Toxoplasma causes widespread tissue necrosis and subsequent calcification throughout the brain parenchyma.
2
Evaluate the constellation of cardiac and ophthalmologic findings.
The presence of an absent red reflex (cataracts) and a continuous machine-like murmur (patent ductus arteriosus) identifies the Rubella virus vignette.
These specific developmental disruptions occurring during the first trimester are the pathognomonic triad of congenital Rubella syndrome.
3
Assess the mucocutaneous and skeletal abnormalities.
The combination of severe serosanguineous rhinitis, palmar/plantar desquamation, and metaphyseal lucencies identifies the Treponema pallidum vignette.
These findings represent the early inflammatory manifestations (osteochondritis and mucocutaneous lesions) specific to early congenital syphilis.

Key Concept

Clinical differentiation of congenital (TORCH) infections based on unique physical examination triads and neuroimaging calcification patterns.
Estimated Time:2m 0s
Question 31Question →

Match the following serum calcium and intact parathyroid hormone (PTH) laboratory profiles to their most likely underlying pathophysiologic diagnosis.

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Items

Elevated serum calcium and elevated intact PTH
Decreased serum calcium and elevated intact PTH
Elevated serum calcium and suppressed intact PTH
Decreased serum calcium and suppressed intact PTH

Matches

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Answer

Elevated Ca/Elevated PTH matches Primary hyperparathyroidism. Decreased Ca/Elevated PTH matches Vitamin D deficiency. Elevated Ca/Suppressed PTH matches Humoral hypercalcemia of malignancy. Decreased Ca/Suppressed PTH matches Iatrogenic parathyroidectomy.
The parathyroid glands maintain calcium homeostasis through a direct negative feedback loop. Normal physiology dictates an inverse relationship: high calcium suppresses PTH, and low calcium stimulates PTH (secondary disorders). A direct relationship (both high or both low) indicates a primary parathyroid disorder.

Step-by-Step Solution

1
Evaluate the serum calcium level in the provided profile.
Determines whether the clinical state is characterized by hypercalcemia or hypocalcemia.
Calcium is the primary regulated variable in this endocrine loop, driving the downstream hormonal response.
2
Evaluate the intact PTH level in the context of the calcium abnormality.
Identifies if the PTH response is appropriate (compensatory) or inappropriate (primary pathology).
An intact negative feedback loop will show PTH moving in the opposite direction of calcium. If PTH moves in the same direction, the parathyroid gland is the source of the pathology.

Key Concept

Calcium and Parathyroid Hormone (PTH) Homeostasis and Feedback Loop
Question 32Question →

Match each clinical presentation of a pediatric exanthem with its most likely causative viral pathogen.

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Items

A 5-year-old child presents with bright red, confluent erythema on both cheeks, followed by a lacy, reticular rash over the trunk and extremities.
A 14-month-old toddler experiences 3 days of high fever. As the fever abruptly resolves, a blanching, pink maculopapular rash appears on the trunk.
A 6-year-old child develops a highly pruritic rash. The lesions consist of macules, papules, clear vesicles on an erythematous base, and crusted scabs, all present simultaneously.
A 3-year-old child presents with low-grade fever, painful oral ulcerations on the posterior pharynx, and small grayish vesicles on the palmar and plantar surfaces.

Matches

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Answer

The presentations correspond to Parvovirus B19 (slapped cheek and reticular rash), HHV-6 (rash after fever resolution), VZV (multi-stage pruritic vesicles), and Coxsackievirus type A (vesicles on hands, feet, and oral mucosa).
Each classic pediatric exanthem has pathognomonic features that allow for clinical diagnosis: Parvovirus B19 causes Erythema infectiosum ('slapped cheeks' and lacy rash), HHV-6 causes Roseola (fever breaks then rash appears), VZV causes Chickenpox (asynchronous lesions in various stages of healing), and Coxsackievirus causes Hand, foot, and mouth disease.

Step-by-Step Solution

1
Analyze the morphology, timing, and distribution of each rash described in the vignettes.
Identified the clinical hallmarks: lacy reticular rash, rash immediately following defervescence, asynchronous vesicular rash, and palm/sole involvement.
Accurate clinical diagnosis of common pediatric viral exanthems relies heavily on recognizing these classic, pathognomonic patterns.

Key Concept

Clinical diagnosis of common pediatric viral exanthems
Question 33Question →

Correlate the following clinical presentations of acute intrapartum and third-trimester emergencies with their primary defining pathophysiologic mechanism.

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Items

A 3232-year-old G2P1 at 3939 weeks gestation with a history of a classical cesarean delivery suddenly develops severe, tearing abdominal pain, a palpable fetal part in the maternal abdomen, and profound fetal bradycardia.
A 2929-year-old G1P0 at 3737 weeks gestation with severe polyhydramnios experiences a sudden onset of extreme dyspnea, cardiovascular collapse, and bleeding from intravenous sites immediately following artificial amniotomy.
A 3636-year-old G4P3 at 3838 weeks gestation with chronic hypertension presents with acute, painful dark vaginal bleeding accompanied by a rigid, board-like uterus and high-frequency, low-amplitude contractions.
A 2828-year-old G2P1 at 3535 weeks gestation with a succenturiate placental lobe experiences painless, bright red vaginal bleeding immediately after spontaneous rupture of membranes, followed by a sinusoidal fetal heart rate tracing.

Matches

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Answer

Match the classical cesarean patient to myometrial disruption; the amniotomy collapse patient to anaphylactoid response; the hypertensive painful bleeding patient to premature detachment; and the succenturiate lobe painless bleeding patient to laceration of fetal vessels.
Each clinical vignette highlights the pathognomonic triad or unique risk factors associated with a distinct obstetric complication. Recognizing these patterns allows for rapid differentiation between mechanisms such as mechanical tearing (rupture), immune-mediated collapse (amniotic fluid embolism), premature separation (abruption), and direct fetal vessel laceration (vasa previa).

Step-by-Step Solution

1
Analyze the patient with a prior classical cesarean section and acute severe pain.
Identified sudden tearing pain, palpable fetal parts, and bradycardia as uterine rupture.
Classical incisions have the highest rate of uterine rupture during labor, presenting with complete transmural disruption.
2
Evaluate the presentation of cardiovascular collapse and coagulopathy immediately after amniotomy.
Recognized amniotic fluid embolism (anaphylactoid syndrome of pregnancy).
Sudden cardiorespiratory failure and coagulopathy upon exposure to amniotic fluid is driven by a massive immune response to fetal antigens.
3
Assess the hypertensive patient with painful bleeding and a rigid uterus.
Diagnosed placental abruption.
Chronic hypertension is a major risk factor for premature placental separation, which causes retroplacental bleeding, pain, and tetanic uterine contractions.
4
Review the scenario of painless bleeding and a sinusoidal heart rate tracing after rupture of membranes.
Diagnosed vasa previa.
Fetal vessels associated with a succenturiate lobe can cross the cervical os and tear during membrane rupture, causing painless bleeding and rapid fetal exsanguination (indicated by a sinusoidal tracing).

Key Concept

Differentiating major obstetric emergencies by their hallmark clinical presentations and underlying pathophysiology.
Question 34Question →

Match each clinical presentation of a trauma patient to the most appropriate next step in management or diagnostic imaging.

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Items

Hemodynamically unstable patient with blunt abdominal trauma and a positive FAST scan showing free intraperitoneal fluid.
Hemodynamically stable patient with blunt abdominal trauma, a seatbelt sign across the lower abdomen, and localized tenderness.
Hemodynamically unstable patient with an 'open book' pelvic fracture, applied pelvic binder, and a negative FAST scan.
Hemodynamically stable patient with a penetrating stab wound to the left lower chest, normal breath sounds, and a benign abdominal exam.
Hemodynamically stable patient with a pubic ramus fracture and gross hematuria following a motor vehicle collision.

Matches

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Answer

1 matches with Immediate exploratory laparotomy; 2 matches with CT scan; 3 matches with Pelvic angiography; 4 matches with Diagnostic laparoscopy; 5 matches with Retrograde cystography.
The correct pairings follow Advanced Trauma Life Support (ATLS) algorithms. Hemodynamic instability with intraperitoneal fluid necessitates exploratory laparotomy. Stable blunt trauma patients require CT imaging. Retroperitoneal pelvic bleeding is managed angiographically. Occult diaphragmatic injuries require laparoscopy, and gross hematuria with a pelvic fracture mandates cystography.

Step-by-Step Solution

1
Assess hemodynamic stability.
Patients are divided into stable and unstable categories.
Hemodynamic instability dictates immediate life-saving interventions over delayed, higher-resolution imaging like CT.
2
Evaluate unstable patients based on FAST results.
Unstable presentation with a positive FAST leads to exploratory laparotomy. Unstable presentation with a negative FAST and pelvic fracture leads to pelvic angiography.
A positive FAST in an unstable patient confirms intra-abdominal hemorrhage. A negative FAST shifts suspicion to retroperitoneal bleeding, which is managed with angiography or extraperitoneal packing.
3
Evaluate stable patients based on mechanism and specific physical findings.
Stable blunt trauma goes to CT. Left thoracoabdominal penetrating trauma goes to laparoscopy. Gross hematuria goes to cystography.
Stable patients can tolerate specific diagnostic workups to uncover occult injuries, such as diaphragmatic tears, hollow viscus injuries, or bladder ruptures.

Key Concept

Algorithmic management of torso trauma based on hemodynamic stability, mechanism of injury, and FAST results.
Question 35Question →

Match each primary acid-base disorder to its corresponding expected physiological compensatory response.

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Items

Primary metabolic acidosis
Primary metabolic alkalosis
Acute primary respiratory acidosis
Chronic primary respiratory acidosis

Matches

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Answer

Metabolic acidosis matches Winters' formula; metabolic alkalosis matches a 0.7 mmHg0.7 \text{ mmHg} PaCO2\text{PaCO}_2 increase per 1 mEq/L1 \text{ mEq/L} HCO3−\text{HCO}_3^- increase; acute respiratory acidosis matches a 1 mEq/L1 \text{ mEq/L} HCO3−\text{HCO}_3^- increase per 10 mmHg10 \text{ mmHg} PaCO2\text{PaCO}_2 increase; and chronic respiratory acidosis matches a 3 to 4 mEq/L3 \text{ to } 4 \text{ mEq/L} HCO3−\text{HCO}_3^- increase per 10 mmHg10 \text{ mmHg} PaCO2\text{PaCO}_2 increase.
Each primary acid-base disorder triggers a predictable and calculable compensatory response. Metabolic acidosis is compensated by hyperventilation, calculated via Winters' formula. Metabolic alkalosis is compensated by hypoventilation, where PaCO2\text{PaCO}_2 rises 0.7 mmHg0.7 \text{ mmHg} per 1 mEq/L1 \text{ mEq/L} rise in HCO3−\text{HCO}_3^-. Acute respiratory acidosis is buffered acutely by cells, raising HCO3−\text{HCO}_3^- by 1 mEq/L1 \text{ mEq/L} per 10 mmHg10 \text{ mmHg} PaCO2\text{PaCO}_2 rise. Chronic respiratory acidosis allows for full renal compensation, raising HCO3−\text{HCO}_3^- by 3 to 4 mEq/L3 \text{ to } 4 \text{ mEq/L} per 10 mmHg10 \text{ mmHg} PaCO2\text{PaCO}_2 rise.

Step-by-Step Solution

1
Identify the primary disturbance and the physiological organ system responsible for compensation.
Metabolic disorders are compensated by the respiratory system (altering PaCO2\text{PaCO}_2), while respiratory disorders are compensated by the renal system (altering HCO3−\text{HCO}_3^-).
Understanding the fundamental physiological mechanism is the first step in applying the correct numerical formula.
2
Correlate metabolic disorders with their specific respiratory compensation rules.
Metabolic acidosis requires evaluation using Winters' formula. Metabolic alkalosis is evaluated using the 0.7 rule.
These established formulas are required to determine if a superimposed secondary acid-base disorder is present.
3
Correlate respiratory disorders with their specific acute versus chronic renal compensation rules.
Acute respiratory acidosis causes a minor HCO3−\text{HCO}_3^- shift (1 for 10), while chronic respiratory acidosis allows for robust renal HCO3−\text{HCO}_3^- retention (3 to 4 for 10).
Renal metabolic compensation takes several days to reach maximal efficacy, creating distinctly different expected values for acute versus chronic respiratory conditions.

Key Concept

Acid-base compensation formulas and expected physiological responses.
Estimated Time:1m 0s
Question 36Question →

Match each patient's clinical presentation with the most appropriate antimicrobial stewardship-guided management step.

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Items

A 3030-year-old man with 44 days of nasal congestion, clear rhinorrhea, and facial pressure. He is afebrile.
A 6565-year-old woman admitted with a severe COPD exacerbation characterized by increased dyspnea, increased sputum volume, and increased sputum purulence.
A 2222-year-old woman with a severe sore throat, a temperature of 38.5∘C38.5^\circ\text{C} (101.3∘F101.3^\circ\text{F}), tender cervical lymphadenopathy, and a positive rapid streptococcal antigen test.
A 7575-year-old man with a chronic venous stasis ulcer on his medial malleolus that is weeping clear fluid but has no surrounding erythema, warmth, or purulence.
A 5555-year-old man hospitalized with acute interstitial pancreatitis who develops a fever of 38.2∘C38.2^\circ\text{C} (100.8∘F100.8^\circ\text{F}) on hospital day 22, with no signs of infected necrosis on imaging.

Matches

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Answer

Viral rhinosinusitis matches with supportive care. COPD exacerbation matches with a short course of azithromycin/doxycycline. Streptococcal pharyngitis matches with a 10-day course of penicillin/amoxicillin. The uninfected venous ulcer matches with standard wound care without antibiotics. Sterile acute pancreatitis matches with maintaining intravenous fluids and withholding prophylactic antibiotics.
Each correct pairing reflects the principles of antimicrobial stewardship by ensuring antibiotics are prescribed only when clearly indicated (e.g., COPD exacerbation with cardinal symptoms, confirmed streptococcal pharyngitis) and avoided when not indicated (e.g., viral sinusitis, colonized wound, sterile pancreatitis).

Step-by-Step Solution

1
Evaluate the indication for antibiotics in the patient with acute rhinosinusitis.
The duration of symptoms is only 44 days, indicating a viral etiology.
Antimicrobial stewardship dictates avoiding antibiotics for self-limiting viral illnesses unless symptoms persist for more than 1010 days.
2
Assess the criteria for antimicrobial therapy in the patient with a COPD exacerbation.
The presence of all three cardinal symptoms warrants targeted antibiotic use.
Bacterial triggers are common in severe COPD exacerbations, and antibiotics improve outcomes in this specific subgroup.
3
Determine the management for confirmed streptococcal pharyngitis.
Antibiotic treatment with penicillin or amoxicillin is required.
Treatment eradicates the pathogen, shortens symptom duration, and significantly reduces the risk of acute rheumatic fever.
4
Analyze the need for antibiotics in the patient with a chronic venous ulcer.
Systemic antibiotics are unnecessary.
The ulcer shows no signs of acute infection (erythema, warmth, purulence). Treating colonization promotes antibiotic resistance without providing clinical benefit.
5
Review the role of prophylactic antibiotics in the patient with acute pancreatitis.
Prophylactic antibiotics are contraindicated.
Early fever in pancreatitis is usually due to the systemic inflammatory response syndrome (SIRS), not a bacterial infection.

Key Concept

Antimicrobial Stewardship in Internal Medicine
Question 37Question →

Match each esophageal motility disorder with its most characteristic finding on high-resolution esophageal manometry.

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Items

Achalasia
Diffuse esophageal spasm
Systemic sclerosis (scleroderma) esophageal involvement
Jackhammer esophagus (hypercontractile esophagus)

Matches

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Answer

Achalasia matches with incomplete LES relaxation and absent peristalsis. Diffuse esophageal spasm matches with simultaneous contractions and normal LES relaxation. Systemic sclerosis matches with absent peristalsis and a hypotensive LES. Jackhammer esophagus matches with extremely high-amplitude coordinated contractions.
Each disorder has a unique manometric signature: Achalasia features failed LES relaxation and aperistalsis; diffuse esophageal spasm features simultaneous contractions with normal LES relaxation; systemic sclerosis features aperistalsis with a hypotensive LES; and Jackhammer esophagus features normally coordinated but extremely high-amplitude contractions.

Step-by-Step Solution

1
Identify the core physiological defect in achalasia.
The primary issue is the loss of inhibitory neurons, which prevents the LES from relaxing upon swallowing and abolishes distal esophageal peristalsis.
This directly matches achalasia to 'incomplete LES relaxation and absent peristalsis'.
2
Differentiate diffuse esophageal spasm from other motility disorders.
It presents with uncoordinated, simultaneous contractions while normal LES function is preserved.
This matches diffuse esophageal spasm to 'simultaneous, uncoordinated, non-peristaltic contractions with normal LES relaxation'.
3
Determine the effect of systemic sclerosis on the esophagus.
Smooth muscle fibrosis affects the lower two-thirds of the esophagus, weakening the LES and abolishing peristalsis, causing severe acid reflux.
This matches systemic sclerosis to 'absent peristalsis in the lower two-thirds of the esophagus with a hypotensive LES'.
4
Identify the hallmark of Jackhammer esophagus.
It is a hypercontractile disorder characterized by intense, high-amplitude contractions that are normally coordinated.
This matches Jackhammer esophagus to 'extremely high-amplitude, prolonged, but coordinated peristaltic contractions'.

Key Concept

Diagnosis of esophageal motility disorders relies on high-resolution manometry to evaluate lower esophageal sphincter (LES) relaxation and the pattern of esophageal body peristalsis.
Estimated Time:1m 30s
Question 38Question →

Match each specific burn or environmental injury presentation with the most appropriate immediate or targeted management step.

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Items

A 35-year-old firefighter is rescued from an enclosed structural fire with singed eyebrows, carbonaceous sputum, and progressive hoarseness.
A 42-year-old industrial worker sustains a deep, leathery, circumferential burn to the right lower extremity; pedal pulses are no longer palpable.
A 24-year-old electrician presents after a high-voltage electrical shock; a Foley catheter drains dark, reddish-brown urine.
A 50-year-old laboratory technician spills a solution on their hand and experiences severe, unrelenting pain that is completely out of proportion to the minimal visible skin erythema.

Matches

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Answer

The correct matches pair inhalational injury with early intubation, circumferential burns causing ischemia with escharotomy, electrical injury rhabdomyolysis with aggressive fluid resuscitation, and hydrofluoric acid burns with calcium gluconate.
Each specific burn presentation carries a unique, immediate threat that dictates the next best step: airway loss (inhalational injury) requires intubation; limb ischemia (circumferential burn) requires escharotomy; acute kidney injury (electrical rhabdomyolysis) requires aggressive fluids; and hypocalcemic tissue necrosis (hydrofluoric acid) requires topical calcium.

Step-by-Step Solution

1
Analyze the firefighter's presentation (enclosed fire, carbonaceous sputum, hoarseness).
Identify high risk for imminent airway obstruction from inhalational injury.
Supraglottic edema can progress rapidly and make delayed intubation impossible.
2
Evaluate the industrial worker's pulseless limb with a leathery burn.
Identify burn-induced compartment syndrome.
The inelastic eschar prevents tissue expansion as edema forms, requiring surgical release (escharotomy).
3
Assess the electrician with dark urine following a high-voltage shock.
Identify myoglobinuria secondary to rhabdomyolysis.
Electrical current travels through deep tissues (muscle/bone), causing massive necrosis. Aggressive fluid resuscitation prevents pigment nephropathy.
4
Analyze the laboratory technician's pain out of proportion to visible injury.
Identify hydrofluoric acid exposure.
Fluoride ions penetrate tissue and deplete local calcium, causing severe nerve pain and tissue death, necessitating calcium gluconate therapy.

Key Concept

Immediate management of specific life- and limb-threatening burn complications
Question 39Question →

Match each patient's clinical presentation and laboratory evaluation to the most likely underlying diagnosis or pathophysiologic mechanism.

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Items

A 4444-year-old woman with weight gain and bruising; evaluation shows elevated 2424-hour urine free cortisol, plasma ACTH of 3 pg/mL3 \text{ pg/mL} (normal 10−60 pg/mL10-60 \text{ pg/mL}), and lack of cortisol suppression following an 8-mg8\text{-mg} overnight dexamethasone test.
A 3535-year-old woman with amenorrhea and proximal muscle weakness; evaluation shows elevated 2424-hour urine free cortisol, plasma ACTH of 70 pg/mL70 \text{ pg/mL} (normal 10−60 pg/mL10-60 \text{ pg/mL}), and >50%>50\% cortisol suppression following an 8-mg8\text{-mg} overnight dexamethasone test.
A 6565-year-old man with a 4040-pack-year smoking history and severe hypokalemia; evaluation shows markedly elevated 2424-hour urine free cortisol, plasma ACTH of 450 pg/mL450 \text{ pg/mL} (normal 10−60 pg/mL10-60 \text{ pg/mL}), and lack of cortisol suppression following an 8-mg8\text{-mg} overnight dexamethasone test.
A 5252-year-old woman with rheumatoid arthritis presenting with central obesity, thinning skin, and osteopenia; evaluation shows a morning serum cortisol of 2 μg/dL2\ \mu\text{g/dL} (normal 5−25 μg/dL5-25\ \mu\text{g/dL}) and plasma ACTH of <5 pg/mL<5 \text{ pg/mL} (normal 10−60 pg/mL10-60 \text{ pg/mL}).

Matches

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Answer

Patient 1 matches autonomous adrenocortical cortisol hypersecretion. Patient 2 matches ACTH-secreting pituitary adenoma. Patient 3 matches paraneoplastic syndrome due to malignancy. Patient 4 matches suppression of the hypothalamic-pituitary-adrenal axis by exogenous agents.
The diagnostic workup for Cushing syndrome follows a rigorous stepwise approach. First, hypercortisolism is confirmed. Next, a plasma ACTH level determines if the cause is ACTH-independent (suppressed ACTH, typically adrenal) or ACTH-dependent (normal to high ACTH, typically pituitary or ectopic). For ACTH-dependent cases, a high-dose dexamethasone suppression test helps distinguish between a pituitary adenoma (which usually suppresses) and ectopic ACTH secretion (which typically does not suppress). Finally, exogenous glucocorticoids mimic Cushing syndrome clinically but suppress the entire HPA axis, resulting in undetectable ACTH and low endogenous cortisol.

Step-by-Step Solution

1
Analyze the 24-hour urine free cortisol and morning serum cortisol levels to confirm the presence of endogenous hypercortisolism or hypocortisolism.
Patients 1, 2, and 3 have elevated urine free cortisol, confirming endogenous Cushing syndrome. Patient 4 has low morning cortisol despite physical signs of Cushing syndrome.
Establishing endogenous cortisol excess is the necessary first step in the algorithm to rule out physiological or iatrogenic variants.
2
Evaluate the plasma ACTH level to determine if the hypercortisolism is ACTH-dependent or ACTH-independent.
Patient 1 has suppressed ACTH (ACTH-independent). Patients 2 and 3 have normal/elevated ACTH (ACTH-dependent). Patient 4 has suppressed ACTH in the setting of low endogenous cortisol.
ACTH levels accurately differentiate primary adrenal causes from pituitary or ectopic causes.
3
Assess the response to the high-dose (8-mg) dexamethasone suppression test for the ACTH-dependent cases.
Patient 2 suppresses >50%, indicating a pituitary source (Cushing disease). Patient 3 does not suppress, indicating an ectopic ACTH source.
Pituitary adenomas generally retain a degree of negative feedback response to high-dose synthetic glucocorticoids, whereas ectopic tumors typically do not.

Key Concept

The diagnostic evaluation of Cushing syndrome relies on establishing hypercortisolism, differentiating ACTH-dependent from ACTH-independent causes via plasma ACTH levels, and utilizing the high-dose dexamethasone suppression test to locate the source of ACTH.
Estimated Time:2m 0s
Question 40Question →

Match each of the following clinical and laboratory profiles with the most likely pathophysiologic diagnosis.

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Items

Low 8 AM serum cortisol, elevated plasma ACTH, hyperkalemia, and hyponatremia
Low 8 AM serum cortisol, decreased plasma ACTH, normal potassium, and mild hyponatremia
Elevated 24-hour urine free cortisol, elevated plasma ACTH, and cortisol suppression with high-dose dexamethasone
Elevated 24-hour urine free cortisol, undetectable plasma ACTH, and no cortisol suppression with high-dose dexamethasone
Normal 8 AM serum cortisol, normal plasma ACTH, elevated plasma aldosterone, and suppressed plasma renin activity

Matches

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Answer

Each profile corresponds to a specific endocrine loop disturbance: Profile 1 to Primary adrenal insufficiency, Profile 2 to Secondary adrenal insufficiency, Profile 3 to Cushing disease, Profile 4 to Adrenal adenoma, and Profile 5 to Primary hyperaldosteronism.
Matching requires accurate identification of feedback loop disruptions. Primary defects show opposite directional changes in stimulating versus target hormones (e.g., high ACTH with low cortisol), whereas secondary defects show same-direction changes (e.g., low ACTH with low cortisol).

Step-by-Step Solution

1
Analyze profiles with low cortisol to distinguish the level of the defect.
Low cortisol with high ACTH and hyperkalemia indicates primary adrenal failure, while low cortisol with low ACTH and normal potassium indicates secondary (pituitary) failure.
The intact aldosterone response (normal potassium) in central adrenal insufficiency differentiates it from primary disease.
2
Analyze profiles with hypercortisolism to identify the specific Cushing syndrome etiology.
High ACTH that suppresses with high-dose dexamethasone points to Cushing disease (pituitary), while undetectable ACTH without suppression indicates a primary adrenal tumor.
Pituitary adenomas retain partial feedback sensitivity to high-dose steroids, unlike adrenal tumors or ectopic ACTH sources.
3
Evaluate the profile with isolated mineralocorticoid abnormalities.
High aldosterone with low renin and normal cortisol confirms primary hyperaldosteronism.
Autonomous aldosterone secretion suppresses renin via volume expansion and operates independently of ACTH and cortisol.

Key Concept

Diagnosis of adrenal disorders relies on interpreting hormone pairs (e.g., ACTH and Cortisol, Renin and Aldosterone) to distinguish primary adrenal pathology from central (pituitary) defects.
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