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Question 1101Question →

Match each clinical presentation describing a patient with renal dysfunction to the most characteristic urinalysis sediment finding associated with their underlying pathology.

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Items

A 65-year-old man who develops an acute increase in serum creatinine three days after a prolonged episode of septic shock.
A 35-year-old woman with a history of systemic lupus erythematosus presenting with hypertension, edema, and new-onset hematuria.
A 28-year-old man presenting with acute kidney injury, fever, maculopapular rash, and arthralgias two weeks after starting omeprazole.
A 55-year-old man with long-standing diabetes mellitus presenting with generalized edema and a urine protein excretion of 5.25.2 g/day.

Matches

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Answer

Septic shock matches with muddy brown granular casts (ATN). Lupus nephritis matches with red blood cell casts (nephritic syndrome). Omeprazole-induced AKI matches with white blood cell casts (AIN). Diabetic nephropathy matches with oval fat bodies (nephrotic syndrome).
Urinalysis sediment provides critical clues to the etiology of renal dysfunction. Muddy brown casts represent sloughed epithelial cells in ATN. Red blood cell casts represent bleeding through an inflamed glomerulus in nephritic syndromes. White blood cell casts represent interstitial inflammation in AIN. Oval fat bodies represent lipiduria secondary to the hyperlipidemia of nephrotic syndrome.

Step-by-Step Solution

1
Analyze the first presentation: Septic shock.
Identified as ischemic injury leading to Acute Tubular Necrosis (ATN).
Hypoperfusion from shock causes ischemic damage to the metabolically active renal tubules, shedding muddy brown casts.
2
Analyze the second presentation: SLE with hematuria and hypertension.
Identified as glomerulonephritis (nephritic syndrome).
Glomerular inflammation allows red blood cells to leak into the tubules, creating dysmorphic red blood cells and red blood cell casts.
3
Analyze the third presentation: Fever, rash, and AKI after omeprazole.
Identified as Acute Interstitial Nephritis (AIN).
Drugs like proton pump inhibitors and NSAIDs can trigger an allergic hypersensitivity reaction in the renal interstitium, producing white blood cell casts and eosinophils.
4
Analyze the fourth presentation: Diabetes with massive proteinuria.
Identified as Nephrotic Syndrome.
Protein excretion over 3.53.5 g/day defines nephrotic syndrome. The resulting hyperlipidemia causes lipiduria, which forms oval fat bodies and fatty casts.

Key Concept

Correlation of distinct acute kidney injury and chronic kidney disease syndromes with their pathognomonic urinalysis findings.
Estimated Time:1m 30s
Question 1102Question →

Match each of the following clinical laboratory profiles to its most likely underlying pathophysiologic diagnosis. Assume the following reference ranges for all profiles:

ParameterReference Range
Serum sodium136-145 mEq/L
Serum potassium3.5-5.0 mEq/L
Serum cortisol (8 AM)5-25 μ\mug/dL
Plasma ACTH10-60 pg/mL
Plasma renin activity (PRA)0.6-4.3 ng/mL/h
Serum aldosterone4-15 ng/dL

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Items

Cortisol: 41 μ\mu g/dL, ACTH: 210 pg/mL, Na: 146 mEq/L, K: 2.6 mEq/L, PRA: 0.1 ng/mL/h, Aldo: 2 ng/dL
Cortisol: 2 μ\mu g/dL, ACTH: 180 pg/mL, Na: 130 mEq/L, K: 5.6 mEq/L, PRA: 12.0 ng/mL/h, Aldo: 1 ng/dL
Cortisol: 3 μ\mu g/dL, ACTH: 6 pg/mL, Na: 136 mEq/L, K: 4.2 mEq/L, PRA: 1.5 ng/mL/h, Aldo: 8 ng/dL
Cortisol: 4 μ\mu g/dL, ACTH: 250 pg/mL, Na: 145 mEq/L, K: 2.8 mEq/L, PRA: 0.2 ng/mL/h, Aldo: 1 ng/dL

Matches

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Answer

The correct matches are: Profile A matches Ectopic ACTH syndrome, Profile B matches Primary adrenal insufficiency, Profile C matches Central adrenal insufficiency, and Profile D matches 11-beta-hydroxylase deficiency.
Accurate diagnosis of adrenal axis disorders demands integrating the glucocorticoid and mineralocorticoid pathways. Ectopic ACTH syndrome (Profile 1) and 11-beta-hydroxylase deficiency (Profile 4) both trigger mineralocorticoid receptors (via cortisol crossover and DOC, respectively), leading to identical downstream effects: sodium retention, hypokalemia, and suppressed renin/aldosterone. They are differentiated strictly by their cortisol levels (massively high vs. low). Primary (Profile 2) and central (Profile 3) adrenal insufficiency both have low cortisol but are distinguished by ACTH levels (high vs. low) and mineralocorticoid integrity (deficient vs. intact).

Step-by-Step Solution

1
Analyze the glucocorticoid axis by evaluating 8 AM Cortisol and ACTH.
Profile 1 shows ACTH-dependent hypercortisolism. Profile 2 and 4 show ACTH-dependent hypocortisolism (loss of negative feedback or enzyme block). Profile 3 shows ACTH-independent hypocortisolism (central defect).
This establishes whether the primary defect is in the pituitary, the adrenal gland, or an ectopic source, and identifies if the condition is an excess or a deficiency state.
2
Analyze the mineralocorticoid axis by evaluating sodium, potassium, renin (PRA), and aldosterone.
Profiles 1 and 4 show mineralocorticoid excess (hypokalemia, low PRA, low aldosterone). Profile 2 shows mineralocorticoid deficiency (hyperkalemia, high PRA, low aldosterone). Profile 3 shows an intact mineralocorticoid axis (normal potassium, PRA, and aldosterone).
This distinguishes between forms of adrenal insufficiency (primary vs. central) and identifies the exact source of mineralocorticoid receptor activation (cortisol crossover vs. DOC vs. aldosterone).
3
Synthesize the findings to confirm diagnoses.
Profile 1 combines hypercortisolism with mineralocorticoid excess (Ectopic ACTH). Profile 2 combines hypocortisolism with mineralocorticoid deficiency (Primary insufficiency). Profile 3 shows pure hypocortisolism (Central insufficiency). Profile 4 combines hypocortisolism with mineralocorticoid excess via DOC (11-beta-hydroxylase deficiency).
Combining both axes is necessary to differentiate conditions like ectopic ACTH from 11-beta-hydroxylase deficiency, which both present with hypokalemia and low renin/aldosterone but completely opposite cortisol levels.

Key Concept

Complex adrenal laboratory interpretation requires simultaneous analysis of the glucocorticoid (ACTH/Cortisol) and mineralocorticoid (Renin/Aldosterone/Potassium) axes to distinguish distinct forms of adrenal excess and insufficiency.
Question 1103Question →

Match each clinical presentation of community-acquired pneumonia (CAP) with the most appropriate empiric antimicrobial regimen based on current clinical guidelines.

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Items

A 24-year-old woman with no significant past medical history diagnosed with community-acquired pneumonia in the ambulatory clinic.
A 68-year-old man with chronic obstructive pulmonary disease and poorly controlled diabetes diagnosed with community-acquired pneumonia in the ambulatory clinic.
A 50-year-old man without significant comorbidities who requires hospital admission to the general medical ward for community-acquired pneumonia.
A 45-year-old woman admitted to the intensive care unit for rapidly progressive community-acquired pneumonia that developed five days after an influenza A infection.

Matches

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Answer

Healthy outpatients match with oral amoxicillin; outpatients with comorbidities match with oral amoxicillin-clavulanate and azithromycin; general ward inpatients match with intravenous ceftriaxone and azithromycin; and ICU inpatients with recent influenza match with intravenous ceftriaxone, azithromycin, and vancomycin.
The correct matches strictly follow the ATS/IDSA guidelines for community-acquired pneumonia, which stratify therapy based on outpatient vs. inpatient status, the presence of comorbidities, and specific risk factors for resistant organisms like MRSA.

Step-by-Step Solution

1
Assess the site of care for each patient based on clinical severity.
Patients 1 and 2 are treated in the outpatient setting. Patient 3 is admitted to the general medical ward. Patient 4 is admitted to the intensive care unit.
The initial branch point in community-acquired pneumonia treatment algorithms is determining the appropriate site of care (outpatient, inpatient floor, or ICU).
2
Evaluate each patient for the presence of major comorbidities or specific risk factors.
Patient 1 has no comorbidities. Patient 2 has COPD and diabetes. Patient 3 has no specific risk factors. Patient 4 has a recent influenza infection.
Comorbidities require expanding outpatient coverage to include beta-lactamase producing bacteria. A recent influenza infection significantly increases the risk of secondary methicillin-resistant Staphylococcus aureus (MRSA) pneumonia.
3
Select the guideline-recommended empiric antimicrobial regimen for each stratified patient profile.
Patient 1: Amoxicillin. Patient 2: Amoxicillin-clavulanate and azithromycin. Patient 3: Ceftriaxone and azithromycin. Patient 4: Ceftriaxone, azithromycin, and vancomycin.
This step ensures comprehensive coverage of expected typical and atypical pathogens while adhering to antibiotic stewardship principles by avoiding unnecessarily broad agents.

Key Concept

Empiric antimicrobial selection for community-acquired pneumonia is stratified by the required site of care (outpatient vs. inpatient ward vs. intensive care unit), the presence of patient comorbidities, and specific risk factors for resistant pathogens such as MRSA.
Estimated Time:2m 0s
Question 1104Question →

Match each clinical vignette describing a patient with a renal disorder to the most characteristic histopathologic or immunofluorescent finding expected on their renal biopsy.

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Items

A 62-year-old man with a history of chronic sinusitis and epistaxis presents with rapidly progressive oliguria. Urinalysis shows dysmorphic red blood cells and red blood cell casts. Serum testing is positive for PR3-ANCA.
A 34-year-old woman with a history of recurrent early fetal loss and a previous deep vein thrombosis develops sudden oliguria and severe hypertension. Laboratory studies reveal thrombocytopenia and schistocytes on a peripheral blood smear.
A 55-year-old man with severe, poorly controlled rheumatoid arthritis for 20 years presents with profound peripheral edema. Laboratory studies show a serum albumin of 2.1 g/dL and a 24-hour urine protein excretion of 6.5 g.
A 28-year-old man develops gross hematuria 48 hours after the onset of a mild upper respiratory tract infection. His serum complement levels are normal. He reports a similar self-resolving episode three years ago.
A 60-year-old man with recently diagnosed lung adenocarcinoma presents with sudden-onset left flank pain, a new left-sided varicocele, and massive lower extremity edema. His urine protein-to-creatinine ratio is 8.0 g/g.

Matches

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Answer

The correct pairings match Granulomatosis with polyangiitis to pauci-immune crescents, Antiphospholipid syndrome TMA to fibrin thrombi, Rheumatoid arthritis-induced amyloidosis to Congo red positivity, IgA nephropathy to mesangial IgA, and Membranous nephropathy (with renal vein thrombosis) to 'spike and dome' subepithelial deposits.
Each clinical vignette provides distinct clues to a specific nephropathy. Granulomatosis with polyangiitis presents with systemic vasculitis (sinusitis) and PR3-ANCA, correlating with pauci-immune crescents. Antiphospholipid syndrome can trigger a secondary thrombotic microangiopathy, characterized by fibrin thrombi and schistocytes without immune complexes. Chronic inflammation from rheumatoid arthritis causes AA amyloidosis, definitively diagnosed via Congo red stain. IgA nephropathy uniquely presents with synpharyngitic hematuria and mesangial IgA deposits. Lastly, membranous nephropathy is heavily associated with solid malignancies and has a high propensity for renal vein thrombosis (causing sudden flank pain and a new left varicocele), showing subepithelial 'spike and dome' deposits on biopsy.

Step-by-Step Solution

1
Analyze each patient's clinical history, physical exam, and laboratory findings to establish the primary clinical diagnosis.
Identified Granulomatosis with polyangiitis (GPA), Antiphospholipid syndrome (APS) with thrombotic microangiopathy (TMA), Secondary AA Amyloidosis, IgA Nephropathy, and Membranous Nephropathy with renal vein thrombosis.
A correct clinical diagnosis is required to deduce the corresponding histopathology, as biopsy findings are pathognomonic for these syndromes.
2
Correlate each clinical diagnosis with its specific biopsy findings on light microscopy, immunofluorescence, and electron microscopy.
Matched pauci-immune crescents to GPA, fibrin thrombi to TMA, Congo red positivity to amyloidosis, mesangial IgA to IgA nephropathy, and subepithelial 'spike and dome' deposits to membranous nephropathy.
Renal pathology is defined by specific microscopic and immunologic patterns that confirm the clinical suspicion and dictate further management.

Key Concept

Correlation of complex clinical nephrology syndromes and their associated complications with pathognomonic renal biopsy findings.
Estimated Time:3m 0s
Question 1105Question →

Congenital infections (often referred to as TORCH infections) can present with distinct clinical syndromes in the neonatal period. Match each characteristic clinical presentation described below to its most likely causative pathogen.

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Items

Congenital Cytomegalovirus (CMV)
Congenital Toxoplasmosis
Congenital Rubella Syndrome
Congenital Syphilis

Matches

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Answer

The accurate pairings link Cytomegalovirus to periventricular calcifications and microcephaly; Toxoplasmosis to diffuse calcifications and hydrocephalus; Rubella to cataracts, deafness, and patent ductus arteriosus; and Syphilis to snuffles and a palmar/plantar rash.
Each classic congenital infection produces a distinct, recognizable pattern of neonatal organ system involvement that dictates the accurate match.

Step-by-Step Solution

1
Evaluate the clinical vignette describing hydrocephalus and diffuse calcifications.
Match this presentation to Congenital Toxoplasmosis.
These findings represent the classic triad of toxoplasmosis, which often involves the brain parenchyma directly.
2
Evaluate the clinical vignette describing periventricular calcifications and microcephaly.
Match this presentation to Congenital Cytomegalovirus (CMV).
CMV preferentially affects the germinal matrix around the ventricles, causing periventricular calcifications and inhibited brain growth (microcephaly).
3
Evaluate the clinical vignette featuring cataracts, hearing loss, and a continuous machine-like murmur (PDA).
Match this presentation to Congenital Rubella Syndrome.
This is the classic rubella triad, distinguishing it as the primary congenital infection associated with severe cardiac defects.
4
Evaluate the clinical vignette featuring snuffles, a desquamating rash on the palms and soles, and bone abnormalities.
Match this presentation to Congenital Syphilis.
Syphilitic rhinitis and palmar/plantar rashes are pathognomonic for early congenital syphilis.

Key Concept

Clinical differentiation of common congenital (TORCH) infections
Estimated Time:1m 0s
Question 1106Question →

Match each patient's clinical presentation with the classic renal biopsy finding most likely to be seen in their condition.

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Items

A 32-year-old woman with systemic lupus erythematosus presents with hypertension, erythrocyte casts, and a rising serum creatinine.
A 48-year-old man with chronic hepatitis C and mixed cryoglobulinemia develops new-onset hematuria and proteinuria.
A 55-year-old man with untreated HIV infection presents with severe generalized edema and 8 g/day of proteinuria.
A 60-year-old man with recently diagnosed colon cancer presents with anasarca, normal renal function, and heavy proteinuria.
A 22-year-old man with a family history of renal failure presents with microscopic hematuria, sensorineural deafness, and anterior lenticonus.

Matches

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Answer

DPGN corresponds to wire loops; MPGN corresponds to tram-track appearance; FSGS corresponds to segmental sclerosis; Membranous nephropathy corresponds to spike and dome pattern; Alport syndrome corresponds to basket-weave appearance.
Each vignette represents a classic systemic trigger for a specific glomerular disease. By recognizing the associations (SLE with DPGN, HCV with MPGN, HIV with FSGS, solid tumor with Membranous Nephropathy, and type IV collagen defect with Alport syndrome), one can definitively pair the clinical presentation with its pathognomonic microscopic description.

Step-by-Step Solution

1
Analyze the SLE vignette (left_1).
Identifies Diffuse Proliferative Glomerulonephritis (DPGN).
SLE with nephritic syndrome and active urinary sediment points to DPGN, which matches with 'wire loop' subendothelial deposits.
2
Analyze the Hepatitis C and cryoglobulinemia vignette (left_2).
Identifies Membranoproliferative Glomerulonephritis (MPGN) Type 1.
Chronic HCV and cryoglobulinemia are strong triggers for MPGN, matching with mesangial interposition and the 'tram-track' appearance.
3
Analyze the HIV infection vignette (left_3).
Identifies Focal Segmental Glomerulosclerosis (FSGS).
Uncontrolled HIV is classically associated with the collapsing variant of FSGS, which presents with massive proteinuria and segmental sclerosis.
4
Analyze the colon cancer vignette (left_4).
Identifies Membranous Nephropathy.
Solid organ malignancies can precipitate secondary Membranous Nephropathy, matching the subepithelial 'spike and dome' appearance.
5
Analyze the familial deafness and lenticonus vignette (left_5).
Identifies Alport Syndrome.
The clinical triad is pathognomonic for Alport syndrome, caused by a type IV collagen defect, matching the 'basket-weave' GBM finding.

Key Concept

Correlation of systemic diseases with secondary glomerular pathologies and their classic microscopic findings.
Estimated Time:2m 0s
Question 1107Question →

Review the four distinct patient laboratory profiles concerning calcium and bone metabolism. Reference ranges: Calcium 8.4-10.2 mg/dL; Phosphorus 2.5-4.5 mg/dL; Intact PTH 15-65 pg/mL; 25-hydroxyvitamin D 20-50 ng/mL; 1,25-dihydroxyvitamin D 18-72 pg/mL. Assign each laboratory profile to the most accurate underlying pathophysiologic etiology.

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Items

Profile 1: Calcium 11.2 mg/dL, phosphorus 2.4 mg/dL, intact PTH 10 pg/mL, 1,25-dihydroxyvitamin D 12 pg/mL
Profile 2: Calcium 11.6 mg/dL, phosphorus 2.2 mg/dL, intact PTH 125 pg/mL, urine calcium-to-creatinine clearance ratio (UCCR) 0.035
Profile 3: Calcium 11.1 mg/dL, phosphorus 3.2 mg/dL, intact PTH 58 pg/mL, urine calcium-to-creatinine clearance ratio (UCCR) 0.006
Profile 4: Calcium 8.1 mg/dL, phosphorus 2.1 mg/dL, intact PTH 155 pg/mL, 25-hydroxyvitamin D 9 ng/mL

Matches

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Answer

Profile 1 correlates with Humoral hypercalcemia of malignancy; Profile 2 correlates with Primary hyperparathyroidism; Profile 3 correlates with Familial hypocalciuric hypercalcemia; Profile 4 correlates with Severe vitamin D deficiency.
The calcium-PTH axis must be interpreted stepwise. High calcium with suppressed PTH implies a non-parathyroid source (e.g., PTHrP in malignancy). High calcium with normal/elevated PTH indicates a parathyroid-dependent source, requiring UCCR to distinguish primary hyperparathyroidism from FHH. Low calcium with low phosphorus implies vitamin D deficiency, as PTH is elevated but cannot compensate without sufficient vitamin D substrate.

Step-by-Step Solution

1
Evaluate Profile 1's PTH level in the context of hypercalcemia.
PTH is appropriately suppressed (10 pg/mL).
This rules out PTH-dependent causes. The low 1,25-dihydroxyvitamin D further differentiates PTHrP-mediated hypercalcemia from extrarenal calcitriol production (e.g., sarcoidosis).
2
Analyze Profile 2 and Profile 3, which both feature hypercalcemia with unsuppressed PTH.
Profile 2 has a UCCR > 0.02, while Profile 3 has a UCCR < 0.01.
UCCR is essential to differentiate primary hyperparathyroidism (high relative urine calcium clearance) from FHH (impaired renal calcium sensing leading to hypocalciuria).
3
Assess Profile 4's calcium and phosphorus levels.
Both are low, accompanied by an elevated PTH and low 25-hydroxyvitamin D.
Low vitamin D leads to decreased intestinal calcium and phosphorus absorption, triggering a secondary rise in PTH, which further lowers phosphorus via phosphaturia.

Key Concept

Differentiation of hypercalcemic and hypocalcemic disorders using intact PTH, phosphorus, 1,25-dihydroxyvitamin D, and urine calcium-to-creatinine clearance ratio.
Estimated Time:1m 30s
Question 1108Question →

Match each clinical vignette describing a patient's presentation to the autoantibody profile most closely associated with their underlying condition.

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Items

A 52-year-old woman with a history of recurrent dental caries presents with a 6-month history of foreign body sensation in her eyes and recent bilateral swelling of the preauricular area.
A 34-year-old woman presents with a 3-month history of swollen fingers, episodic color changes in her hands upon cold exposure, and recent difficulty rising from a chair.
A 48-year-old man develops progressive difficulty climbing stairs over 2 months, accompanied by an erythematous rash on his upper eyelids and scaling plaques on his knuckles.
A 42-year-old woman presents with rapidly progressive skin tightening extending proximal to her elbows over 4 months, gastroesophageal reflux, and new-onset exertional dyspnea.

Matches

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Answer

The Sjögren syndrome vignette matches with Anti-Ro/SSA and Anti-La/SSB antibodies; the mixed connective tissue disease vignette matches with Anti-U1 RNP antibodies; the dermatomyositis vignette matches with Anti-Jo-1 antibodies; the diffuse cutaneous systemic sclerosis vignette matches with Anti-Scl-70 antibodies.
Each clinical vignette provides classic pathognomonic features of a distinct rheumatologic condition, which corresponds to a highly specific serologic marker. Sjögren syndrome is characterized by sicca symptoms and Anti-Ro/La antibodies. Mixed connective tissue disease presents with overlapping features and requires Anti-U1 RNP antibodies for diagnosis. Dermatomyositis presents with characteristic rashes and muscle weakness, and is frequently associated with Anti-Jo-1 antibodies. Diffuse cutaneous systemic sclerosis involves widespread skin thickening and internal organ fibrosis, which is linked to Anti-Scl-70 antibodies.

Step-by-Step Solution

1
Analyze the first clinical vignette to identify the underlying diagnosis.
Sjögren syndrome is identified.
The patient has classic sicca symptoms (dry eyes, dental caries from dry mouth) and parotid gland enlargement.
2
Identify the primary autoantibody profile for Sjögren syndrome.
Anti-Ro/SSA and Anti-La/SSB antibodies.
These are the most specific serologic markers associated with this condition.
3
Evaluate the second vignette for diagnostic features.
Mixed connective tissue disease is diagnosed.
The patient presents with overlapping symptoms from multiple connective tissue diseases (sclerosis, myositis, Raynaud phenomenon).
4
Identify the essential serologic marker for mixed connective tissue disease.
Anti-U1 RNP antibodies.
High titers of these antibodies are required for the diagnosis of MCTD.
5
Analyze the third vignette.
Dermatomyositis is identified.
The presentation of progressive proximal muscle weakness combined with a heliotrope rash and Gottron papules is classic.
6
Identify the common myositis-specific antibody for this condition.
Anti-Jo-1 antibodies.
This is a key antibody in dermatomyositis, especially when associated with anti-synthetase syndrome features.
7
Examine the fourth vignette.
Diffuse cutaneous systemic sclerosis is identified.
The patient has widespread skin thickening proximal to the elbows and visceral organ involvement (interstitial lung disease, gastroesophageal reflux).
8
Identify the autoantibody specific to diffuse systemic sclerosis.
Anti-Scl-70 antibodies.
This antibody is a specific marker for the diffuse subtype of scleroderma, contrasting with anti-centromere antibodies seen in the limited subtype.

Key Concept

Autoantibody profiles and classic clinical presentations in systemic rheumatologic diseases.
Question 1109Question →

Systemic vasculitides often present with a wide spectrum of overlapping clinical manifestations, but specific patterns of organ involvement, histological features, and autoantibody associations can help differentiate them. Match each of the following vasculitis diagnoses with its classic clinical presentation and associated laboratory findings.

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Items

Granulomatosis with polyangiitis (GPA)
Eosinophilic granulomatosis with polyangiitis (EGPA)
Microscopic polyangiitis (MPA)
Polyarteritis nodosa (PAN)
IgA vasculitis

Matches

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Answer

Granulomatosis with polyangiitis (GPA) matches with upper respiratory tract involvement, lower respiratory tract nodules, and PR3-ANCA. Eosinophilic granulomatosis with polyangiitis (EGPA) matches with asthma, eosinophilia, and MPO-ANCA. Microscopic polyangiitis (MPA) matches with pulmonary capillaritis and glomerulonephritis without granulomas, associated with MPO-ANCA. Polyarteritis nodosa (PAN) matches with medium vessel inflammation sparing the lungs, associated with Hepatitis B. IgA vasculitis matches with palpable purpura, arthralgias, and abdominal pain.
Each vasculitis has a distinct clinical and pathophysiological profile that allows for specific identification based on organ involvement, histological presence of granulomas, and specific autoantibodies (such as PR3-ANCA and MPO-ANCA).

Step-by-Step Solution

1
Identify the key clinical features and serological markers for Granulomatosis with polyangiitis.
Matches with upper airway disease, lung nodules, glomerulonephritis, and PR3-ANCA.
GPA is defined by this classic clinical triad and its strong association with PR3-ANCA.
2
Identify the unique features of Eosinophilic granulomatosis with polyangiitis.
Matches with asthma, allergic rhinosinusitis, peripheral neuropathy, and eosinophilia.
The presence of asthma and significant eosinophilia are the defining features of EGPA among the ANCA-associated vasculitides.
3
Differentiate Microscopic polyangiitis from GPA.
Matches with necrotizing glomerulonephritis and pulmonary capillaritis, but lacks granulomas and upper airway disease, associated with MPO-ANCA.
MPA causes pulmonary-renal syndrome similar to GPA but is histologically distinct (no granulomas) and typically MPO-ANCA positive.
4
Identify the characteristic features of Polyarteritis nodosa.
Matches with segmental inflammation of medium arteries sparing the lungs, associated with hepatitis B.
Lung sparing and a strong association with hepatitis B virus are classic high-yield identifiers for PAN.
5
Identify the classic presentation of IgA vasculitis.
Matches with palpable purpura, arthralgias, and abdominal pain.
This is the classic tetrad of symptoms resulting from IgA immune complex deposition in small vessels.

Key Concept

Clinical and serological differentiation of systemic vasculitides.
Question 1110Question →

Neonatal respiratory distress can result from a variety of pulmonary and extrapulmonary conditions. Differentiating these conditions often relies heavily on the initial radiographic evaluation. Match each neonatal respiratory condition below to its most characteristic initial chest radiograph presentation.

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Items

Respiratory distress syndrome
Transient tachypnea of the newborn
Meconium aspiration syndrome
Neonatal pneumothorax

Matches

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Answer

Respiratory distress syndrome matches with diffuse reticulogranular appearance and low lung volumes. Transient tachypnea of the newborn matches with prominent perihilar streaking and fluid in fissures. Meconium aspiration syndrome matches with hyperinflation and patchy infiltrates. Neonatal pneumothorax matches with unilateral radiolucency lacking lung markings.
Correct matching relies on understanding the distinct mechanical and pathophysiologic mechanisms of neonatal pulmonary disorders. Surfactant deficiency (RDS) collapses alveoli, reducing lung volumes and creating a ground-glass opacity. Retained fetal fluid (TTN) widens lymphatic spaces, causing perihilar streaking and fluid in fissures while maintaining lung volume. Airway obstruction by meconium (MAS) causes air trapping and hyperinflation alongside patchy infiltrates. Pleural air accumulation (pneumothorax) physically displaces the lung, appearing as a hyperlucent space without vascular markings.

Step-by-Step Solution

1
Analyze the pathophysiology of Respiratory distress syndrome (RDS).
Identify that premature infants lack adequate surfactant, leading to increased surface tension and diffuse alveolar collapse.
This structural collapse directly translates to the classic radiographic findings of low lung volumes and a reticulogranular (ground-glass) pattern.
2
Analyze the pathophysiology of Transient tachypnea of the newborn (TTN).
Identify that TTN involves delayed clearance of fetal lung fluid, often seen in term infants or those delivered via cesarean section.
Retained fluid collects in the perihilar lymphatics and interlobar fissures, presenting as prominent streaking without the loss of lung volume seen in RDS.
3
Analyze the pathophysiology of Meconium aspiration syndrome (MAS).
Identify that aspirated meconium causes both a chemical pneumonitis and partial airway obstruction.
The partial obstruction creates a 'ball-valve' effect where air enters but cannot escape, causing hyperinflation, while chemical irritation creates coarse, patchy infiltrates.
4
Analyze the pathophysiology of Neonatal pneumothorax.
Identify that high positive pressure (e.g., from mechanical ventilation or MAS air trapping) can rupture alveoli, leaking air into the pleural space.
Free air in the pleural cavity appears hyperlucent (dark) and compresses the underlying lung, leaving the pleural space devoid of pulmonary vascular markings.

Key Concept

Radiographic differentiation of neonatal respiratory distress
Question 1111Question →

Match each clinical scenario with its most likely primary acid-base disorder.

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Items

Severe diarrhea
Opiate overdose
Protracted vomiting
Salicylate toxicity (early phase)

Matches

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Answer

Severe diarrhea causes normal anion gap metabolic acidosis; opiate overdose causes respiratory acidosis; protracted vomiting causes metabolic alkalosis; early salicylate toxicity causes respiratory alkalosis.
Each clinical condition triggers a specific primary acid-base disturbance: bicarbonate loss in diarrhea (normal gap acidosis), CO2 retention in opiate overdose (respiratory acidosis), H+ loss in vomiting (metabolic alkalosis), and hyperventilation in early salicylate overdose (respiratory alkalosis).

Step-by-Step Solution

1
Identify the primary disturbance in severe diarrhea
Normal anion gap metabolic acidosis
Gastrointestinal loss of bicarbonate leads to a non-anion gap (hyperchloremic) metabolic acidosis.
2
Identify the primary disturbance in opiate overdose
Respiratory acidosis
Central respiratory depression leads to hypoventilation and retention of carbon dioxide.
3
Identify the primary disturbance in protracted vomiting
Metabolic alkalosis
Loss of gastric hydrochloric acid and volume contraction leads to metabolic alkalosis.
4
Identify the primary disturbance in early salicylate toxicity
Respiratory alkalosis
Salicylates directly stimulate the medullary respiratory center, causing hyperventilation and blowing off carbon dioxide.

Key Concept

Primary Acid-Base Disorders and Their Etiologies
Question 1112Question →

Match each commonly prescribed medication with its primary mechanism of inducing acute kidney injury (AKI).

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Items

Gentamicin
Ibuprofen
Nafcillin
Intravenous Acyclovir

Matches

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Answer

Gentamicin causes direct tubular toxicity (ATN). Ibuprofen causes hemodynamically mediated AKI via afferent vasoconstriction. Nafcillin induces an allergic acute interstitial nephritis (AIN). Intravenous acyclovir causes intratubular obstruction via crystal precipitation.
Each medication listed corresponds to a distinct pathophysiological mechanism of acute kidney injury. Aminoglycosides (gentamicin) directly damage the proximal tubule resulting in ATN. NSAIDs (ibuprofen) block the synthesis of vasodilatory prostaglandins, leading to afferent arteriolar vasoconstriction and decreased GFR (prerenal/hemodynamic AKI). Beta-lactams (nafcillin) act as haptens to trigger an allergic, cell-mediated immune response in the renal interstitium (AIN). Acyclovir, particularly when administered intravenously without adequate hydration, crystallizes within the tubular lumen, causing crystal-induced intrarenal obstruction.

Step-by-Step Solution

1
Identify the mechanism of aminoglycoside-induced nephrotoxicity.
Gentamicin causes direct toxic injury to proximal tubular epithelial cells (Acute Tubular Necrosis).
Aminoglycosides accumulate in the proximal tubule cells, leading to cellular necrosis and sloughing into the tubular lumen (muddy brown casts).
2
Identify the mechanism of NSAID-induced nephrotoxicity.
Ibuprofen causes inhibition of vasodilatory prostaglandins leading to afferent arteriolar vasoconstriction.
Prostaglandins normally dilate the afferent arteriole to maintain glomerular filtration rate (GFR). NSAIDs block this, reducing renal blood flow.
3
Identify the mechanism of penicillin-induced nephrotoxicity.
Nafcillin causes an idiosyncratic delayed hypersensitivity reaction in the renal interstitium (Acute Interstitial Nephritis).
Beta-lactam antibiotics are a classic trigger for AIN, characterized by interstitial inflammation often with eosinophiluria.
4
Identify the mechanism of acyclovir-induced nephrotoxicity.
Intravenous acyclovir causes precipitation of insoluble metabolites causing intratubular obstruction.
Acyclovir is poorly soluble in urine and can rapidly form crystals in the tubules, especially in volume-depleted patients, causing intrarenal obstruction.

Key Concept

Mechanisms of drug-induced acute kidney injury (AKI)
Question 1113Question →

Match each patient's clinical presentation with the most accurate underlying pathophysiologic description.

Click a left item, then click its matching right item

Items

A 68-year-old man with a history of severe chronic obstructive pulmonary disease is evaluated in the acute care clinic for worsening somnolence and a productive cough. Arterial blood gas on room air shows a pH of 7.247.24, pCO 2_2 of 7272 mm Hg, and calculated HCO 3−_3^- of 3030 mEq/L.
A 55-year-old man with progressive fatigue and deep, rapid breathing (Kussmaul respirations) has laboratory testing showing Na +^+ 140140 mEq/L, Cl −^- 104104 mEq/L, and HCO 3−_3^- 1212 mEq/L, alongside markedly elevated blood urea nitrogen and creatinine levels.
A 72-year-old woman who recently completed a 10-day course of oral levofloxacin for a respiratory tract infection now presents with profuse, foul-smelling, watery diarrhea. Her laboratory results show a leukocyte count of 22,000/mm322,000 / \text{mm}^3.
A 32-year-old woman recently started on oral methimazole for hyperthyroidism reports to the clinic with a sudden onset of rigors and severe odynophagia. A complete blood count reveals an absolute neutrophil count of 200/mm3200 / \text{mm}^3.

Matches

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Answer

The clinical vignettes correctly match to: COPD exacerbation with acute-on-chronic respiratory acidosis, uremic high anion gap metabolic acidosis, antibiotic-associated Clostridioides difficile colitis, and methimazole-induced agranulocytosis.
Each matching pair requires identifying the primary diagnosis from the vignette and mapping it to its formal pathophysiologic description. The first patient has alveolar hypoventilation (COPD exacerbation). The second has uremic acidosis (high anion gap). The third has C. difficile colitis (microbial dysbiosis). The fourth has methimazole-induced agranulocytosis (immune-mediated myelopoiesis arrest).

Step-by-Step Solution

1
Evaluate the arterial blood gas for the first patient to determine the primary disturbance.
Identified primary respiratory acidosis with partial metabolic compensation.
Allows accurate classification of the acid-base derangement caused by the acute COPD exacerbation.
2
Calculate the anion gap using the formula: Na +^+ - (Cl −^- + HCO 3−_3^-) for the second patient.
The calculated anion gap is 2424 mEq/L, confirming a high anion gap metabolic acidosis.
Differentiates between normal and high anion gap metabolic acidosis in a patient with renal failure.
3
Assess the temporal relationship between levofloxacin use and the onset of profound leukocytosis and diarrhea in the third patient.
Identifies a high clinical suspicion for Clostridioides difficile colitis.
Broad-spectrum antibiotics disrupt normal flora, leading to opportunistic toxigenic infections.
4
Correlate the initiation of methimazole with the profound neutropenia (ANC 200/mm3200 / \text{mm}^3) in the fourth patient.
Identifies drug-induced agranulocytosis.
Prompt recognition of this idiosyncratic drug toxicity is critical to stop the offending agent and prevent fatal sepsis.

Key Concept

Integration of diverse clinical presentations in general internal medicine, requiring multi-step diagnosis of acid-base disturbances, nosocomial infections, and severe adverse drug reactions based on physical findings and laboratory data.
Question 1114Question →

During routine prenatal care, various screening tests and clinical evaluations are utilized to monitor maternal and fetal well-being. Match each specific clinical presentation or screening result with its most appropriate next step in management or physiological interpretation.

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Items

Ultrasound at 12 weeks gestation reveals a nuchal translucency of 3.8 mm; concurrent cell-free DNA testing indicates low risk for fetal aneuploidy.
Maternal serum alpha-fetoprotein drawn at 16 weeks gestation returns markedly elevated at 2.9 multiples of the median.
Midstream urine culture at 10 weeks gestation yields 10510^5 CFU/mL of Group B Streptococcus, successfully treated with appropriate antibiotics.
Laboratory evaluation at 9 weeks gestation demonstrates a suppressed TSH (0.2 mIU/L), elevated total T4, and normal free T4.
Routine examination at 36 weeks gestation reveals a fundal height of 32 cm in a patient with a previously normal growth trajectory.

Matches

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Answer

Pair each clinical scenario with its corresponding management: NT of 3.8mm with fetal echocardiography; elevated MSAFP with comprehensive ultrasound; GBS bacteriuria with omitting the third-trimester swab; suppressed TSH with reassurance for physiologic changes; and fundal height discrepancy with ultrasound for growth restriction.
Each presentation requires an understanding of advanced prenatal care guidelines: structural anomaly risks after normal aneuploidy screening, the workup of elevated MSAFP, lifelong/pregnancy indications for GBS prophylaxis, expected biochemical thyroid changes in pregnancy, and indications for fetal growth ultrasounds.

Step-by-Step Solution

1
Analyze the nuchal translucency and cell-free DNA results.
Identify that increased NT despite normal cfDNA carries a high risk of structural anomalies, primarily cardiac.
Cell-free DNA screens for aneuploidy but does not detect structural defects, requiring detailed fetal echocardiography.
2
Evaluate the elevated MSAFP result at 16 weeks.
Determine that ultrasound is required to visualize potential neural tube or ventral wall defects, or to correct gestational dating.
MSAFP is highly sensitive for open neural tube defects, but dating errors and multiple gestations are common causes of false positive results.
3
Assess the management of early pregnancy GBS bacteriuria.
Conclude that the patient is definitively colonized and requires intrapartum prophylaxis without further screening.
Any GBS bacteriuria during the current pregnancy bypasses the need for the standard late third-trimester culture.
4
Interpret the first-trimester thyroid panel.
Recognize the pattern of suppressed TSH, high total T4, and normal free T4 as a normal physiologic change.
hCG cross-reactivity and estrogen-induced thyroxine-binding globulin production perfectly explain these findings.
5
Evaluate the fundal height discrepancy.
Identify that a 4 cm lag in fundal height at 36 weeks is abnormal and requires investigation.
A size-dates discrepancy of greater than 3 cm necessitates an ultrasound to assess estimated fetal weight and amniotic fluid index.

Key Concept

Interpretation and management of routine prenatal screening and physiological adaptations
Question 1115Question →

Match each patient's clinical and histopathologic presentation with the corresponding defining cytogenetic abnormality and characteristic therapeutic approach.

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Items

A 52-year-old woman presents with early satiety and left upper quadrant fullness. Complete blood count shows a leukocyte count of 75,000/mm3 with absolute basophilia and an elevated lactate dehydrogenase.
A 38-year-old man presents with epistaxis, widespread ecchymoses, and gingival bleeding. Coagulation studies reveal elevated D-dimer, prolonged prothrombin time, and decreased fibrinogen. Smear shows abnormal cells with numerous cytoplasmic needle-like inclusions.
A 10-year-old boy of East African descent is evaluated for a rapidly expanding, non-tender jaw mass. Histology of the mass reveals a high mitotic index with scattered macrophages containing apoptotic debris.
A 62-year-old woman is evaluated for waxing and waning painless cervical and axillary lymphadenopathy. Excisional biopsy demonstrates a nodular proliferation of small cleaved cells lacking macrophages.

Matches

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Answer

Patient 1 (CML) matches with the t(9;22) translocation. Patient 2 (APL) matches with the t(15;17) translocation. Patient 3 (Burkitt Lymphoma) matches with the t(8;14) translocation. Patient 4 (Follicular Lymphoma) matches with the t(14;18) translocation.
Each hematologic malignancy has a defining genetic lesion that dictates its clinical behavior and treatment. CML is driven by the BCR-ABL1 fusion from t(9;22) and is treated with tyrosine kinase inhibitors. APL is driven by the PML-RARA fusion from t(15;17), causing a differentiation block that is reversed by ATRA. Burkitt lymphoma relies on c-MYC overexpression from t(8;14), causing rapid proliferation requiring aggressive chemotherapy. Follicular lymphoma is driven by BCL2 overexpression from t(14;18), preventing apoptosis and presenting as an indolent disease often managed with anti-CD20 therapy.

Step-by-Step Solution

1
Diagnose the specific hematologic malignancy based on the clinical vignette.
Patient 1 has Chronic Myeloid Leukemia. Patient 2 has Acute Promyelocytic Leukemia. Patient 3 has Burkitt Lymphoma. Patient 4 has Follicular Lymphoma.
Synthesizing the presenting symptoms, laboratory abnormalities (e.g., basophilia, DIC panel), and classic histologic descriptions allows for accurate primary diagnosis.
2
Connect the diagnosed malignancy with its defining molecular pathophysiology and treatment strategy.
CML correlates with t(9;22) and tyrosine kinase inhibitors. APL correlates with t(15;17) and all-trans retinoic acid. Burkitt Lymphoma correlates with t(8;14) and intensive chemotherapy. Follicular Lymphoma correlates with t(14;18) and rituximab.
Understanding the specific cytogenetic drivers of leukemias and lymphomas is necessary to determine their corresponding targeted therapeutic interventions.

Key Concept

Molecular cytogenetics and associated targeted therapies in hematologic malignancies.
Estimated Time:1m 30s
Question 1116Question →

A physician is evaluating four different patients in the outpatient clinic who present with varying signs of adrenal dysfunction. Match each patient's clinical presentation and characteristic laboratory profile to the most likely underlying adrenal disorder.

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Items

Primary adrenal insufficiency
Secondary adrenal insufficiency
Primary hyperaldosteronism
Cortisol-producing adrenal adenoma

Matches

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Answer

Primary adrenal insufficiency matches the hyperpigmented patient with high ACTH and hyperkalemia. Secondary adrenal insufficiency matches the patient with prior steroid use, low ACTH, and normal potassium. Primary hyperaldosteronism matches the hypertensive patient with high aldosterone, low renin, and hypokalemia. Cortisol-producing adenoma matches the centrally obese patient with high cortisol and suppressed ACTH.
Each disorder presents with a specific laboratory profile dictated by physiological feedback loops. Primary gland failure results in decreased peripheral hormone and elevated trophic hormone, whereas autonomous peripheral hormone production suppresses the trophic hormone. The preservation of aldosterone in pituitary disease distinguishes it from primary adrenal failure.

Step-by-Step Solution

1
Analyze the hypothalamic-pituitary-adrenal (HPA) axis feedback loop for each clinical presentation.
Identify that primary disorders feature abnormal hormone levels from the adrenal gland with compensatory changes in trophic hormones, while secondary disorders start with abnormal pituitary ACTH.
This fundamental principle distinguishes primary from secondary endocrine pathologies.
2
Differentiate the two forms of adrenal insufficiency based on potassium levels and hyperpigmentation.
The patient with hyperkalemia and hyperpigmentation has primary disease (loss of aldosterone and high ACTH), whereas the patient with normal potassium has secondary disease (intact renin-angiotensin-aldosterone system).
Aldosterone is primarily regulated by the renin-angiotensin-aldosterone system (RAAS), not ACTH, keeping potassium normal in secondary disease.
3
Identify the specific overproduction syndromes based on the isolated hormone excess.
The patient with hypokalemia, hypertension, and suppressed renin has primary hyperaldosteronism. The patient with central obesity and suppressed ACTH has a cortisol-producing adenoma.
Autonomous hormone production exerts negative feedback on normal regulatory mechanisms (renin and ACTH, respectively).

Key Concept

Endocrine feedback loops and the differentiation of primary versus secondary adrenal disorders based on ACTH and electrolyte levels.
Question 1117Question →

Match each patient's clinical presentation of chronic cough with the most appropriate initial pharmacological intervention or management step.

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Items

A 45-year-old man presents with an 8-week history of cough, predominantly at night, associated with frequent throat clearing and a sour taste in his mouth.
A 35-year-old woman presents with a 10-week history of dry cough, accompanied by a sensation of liquid dripping down the back of her throat and cobblestoning of the posterior pharynx.
A 28-year-old man presents with a 3-month history of a nonproductive cough that worsens with exercise and cold air exposure; lung examination is unremarkable.
A 62-year-old woman presents with a 6-month history of dry cough; her medical history is notable for hypertension treated with lisinopril and hydrochlorothiazide.

Matches

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Answer

The correct matches pair GERD with a proton pump inhibitor, upper airway cough syndrome with a first-generation antihistamine-decongestant, cough-variant asthma with an inhaled corticosteroid, and ACE inhibitor-induced cough with medication discontinuation.
Chronic cough is defined as a cough lasting longer than 8 weeks. The most common causes are upper airway cough syndrome (UACS), asthma, gastroesophageal reflux disease (GERD), and medications (specifically ACE inhibitors). Patient 1 has typical GERD symptoms, making a proton pump inhibitor the best next step. Patient 2 describes UACS, which responds to a first-generation antihistamine-decongestant. Patient 3 has cough-variant asthma, appropriately managed with inhaled corticosteroids. Patient 4 is on an ACE inhibitor, which must be discontinued to determine if the cough resolves.

Step-by-Step Solution

1
Analyze each clinical vignette to identify the underlying etiology of the chronic cough.
Patient 1 has GERD, Patient 2 has upper airway cough syndrome, Patient 3 has cough-variant asthma, and Patient 4 has an ACE inhibitor-induced cough.
Identifying the distinct clinical pattern is required before selecting the appropriate empirical therapy.
2
Select the guideline-recommended first-line management for each identified etiology.
GERD requires a PPI; upper airway cough syndrome requires an antihistamine-decongestant; asthma requires inhaled corticosteroids; ACE inhibitor cough requires stopping the drug.
Standard of care dictates specific targeted empirical trials for the most common causes of chronic cough when the chest radiograph is presumed normal.

Key Concept

The evaluation and empirical management of chronic cough (lasting >8 weeks) in adults involves targeting the four most common etiologies: upper airway cough syndrome, asthma, gastroesophageal reflux disease, and ACE inhibitor use.
Question 1118Question →

A 72-hour fasting test is conducted to evaluate adult patients presenting with recurrent episodes of spontaneous fasting hypoglycemia. Match each of the following biochemical profiles (all obtained at the time of symptomatic hypoglycemia with plasma glucose < 45 mg/dL) with the most likely underlying etiology.

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Items

Insulin 45 µU/mL (High), C-peptide 0.1 ng/mL (Low), Proinsulin <5 pmol/L (Low), Negative hypoglycemic drug screen
Insulin 35 µU/mL (High), C-peptide 3.8 ng/mL (High), Proinsulin 55 pmol/L (High), Negative hypoglycemic drug screen
Insulin 42 µU/mL (High), C-peptide 4.0 ng/mL (High), Proinsulin 12 pmol/L (Normal), Positive hypoglycemic drug screen
Insulin 2 µU/mL (Low), C-peptide 0.1 ng/mL (Low), Beta-hydroxybutyrate 0.1 mmol/L (Low), Elevated IGF-II:IGF-I ratio
Insulin 2 µU/mL (Low), C-peptide 0.1 ng/mL (Low), Beta-hydroxybutyrate 4.5 mmol/L (High), Cortisol 2.5 µg/dL (Low)

Matches

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Answer

The correct matches require distinguishing insulin-mediated vs non-insulin-mediated hypoglycemia, identifying the source of excess insulin (endogenous vs exogenous), and utilizing beta-hydroxybutyrate to differentiate causes of appropriately suppressed insulin.
Each match correctly pairs the underlying pathophysiology with its exact biochemical signature during a fasting state. Exogenous insulin lacks C-peptide; insulinomas secrete insulin/C-peptide/proinsulin; sulfonylureas mimic insulinomas but yield a positive drug screen; NICTH suppresses ketones and insulin via IGF-II; and adrenal insufficiency features low cortisol, low insulin, but high ketones due to unsuppressed lipolysis.

Step-by-Step Solution

1
Evaluate the insulin and C-peptide levels relative to the hypoglycemic state.
Separates hyperinsulinemic hypoglycemia (requires high C-peptide to confirm endogenous origin) from hypoinsulinemic hypoglycemia.
Insulin should be suppressed during hypoglycemia. If elevated without C-peptide, it is exogenous. If both are elevated, it is endogenous.
2
For endogenous hyperinsulinemic profiles, evaluate the hypoglycemic drug screen.
Differentiates sulfonylurea/meglitinide ingestion (positive screen) from an autonomous beta-cell tumor like an insulinoma (negative screen).
Secretagogues perfectly mimic the biochemical profile of an insulinoma, making the drug screen the definitive differentiating step.
3
For hypoinsulinemic profiles, evaluate beta-hydroxybutyrate (ketones) and specific hormones (IGF-II, cortisol).
Low ketones with low insulin points to an insulin-mimetic substance (IGF-II from NICTH). High ketones with low insulin points to counter-regulatory failure (adrenal insufficiency).
IGF-II activates insulin receptors, suppressing ketogenesis just as insulin would. Cortisol deficiency causes hypoglycemia but allows robust ketogenesis because insulin is low and no mimetics are present.

Key Concept

Evaluation of fasting hypoglycemia requires a stepwise analysis of insulin, C-peptide, drug screens, and beta-hydroxybutyrate to pinpoint the exact physiological failure point.
Question 1119Question →

Match each classic pediatric clinical presentation with its most likely causative pathogen.

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Items

A 7-year-old with fever, exudative pharyngitis, a strawberry tongue, and a diffuse, fine, blanching sandpaper-like rash.
A 6-year-old with bright red erythema on both cheeks followed by a lacy, reticular rash on the extremities.
A 3-year-old with fever, painful oral vesicles on the buccal mucosa, and tender maculopapular lesions on the palms and soles.
A 5-year-old with an intensely pruritic, generalized rash consisting of papules, vesicles, and crusted lesions appearing simultaneously.
A 2-year-old with sudden onset of high fever, nuchal rigidity, and a rapidly spreading non-blanching purpuric and petechial rash.

Matches

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Answer

The correct pairings are: the sandpaper-like rash with Streptococcus pyogenes (Scarlet fever); the slapped-cheek rash with Parvovirus B19 (Erythema infectiosum); the palmar/plantar vesicles with Coxsackievirus A16 (Hand, foot, and mouth disease); the multi-stage pruritic vesicles with Varicella-zoster virus (Chickenpox); and the purpuric rash with Neisseria meningitidis (Meningococcemia).
Each clinical vignette highlights the pathognomonic features of a distinct pediatric infectious disease. Recognizing these classic patterns (e.g., the sandpaper texture in Scarlet fever, the multi-stage lesions in Varicella) allows for the rapid identification of the causative organism, dictating whether urgent antibiotic therapy or supportive care is required.

Step-by-Step Solution

1
Analyze the first presentation featuring pharyngitis, a strawberry tongue, and a sandpaper-like rash.
Identified as Scarlet fever.
This is the classic toxigenic manifestation of a Streptococcus pyogenes infection.
2
Evaluate the second presentation featuring bright red cheeks and a lacy, reticular rash.
Identified as Erythema infectiosum (Fifth disease).
This biphasic rash pattern is pathognomonic for Parvovirus B19.
3
Assess the third presentation featuring oral vesicles and tender lesions on the palms and soles.
Identified as Hand, foot, and mouth disease.
This specific distribution of lesions is the clinical hallmark of Coxsackievirus A16.
4
Examine the fourth presentation featuring a generalized pruritic rash with papules, vesicles, and crusts simultaneously.
Identified as Chickenpox.
Lesions in multiple stages of development ('dew drops on a rose petal') strongly indicate Varicella-zoster virus.
5
Analyze the fifth presentation featuring high fever, nuchal rigidity, and a non-blanching purpuric rash.
Identified as Meningococcemia.
A rapid-onset petechial/purpuric rash with signs of meningitis is a severe emergency highly suspicious for Neisseria meningitidis.

Key Concept

Accurate clinical diagnosis of pediatric exanthems based on pathognomonic rash morphology and systemic symptoms is essential for identifying the causative pathogen and initiating appropriate management.
Estimated Time:1m 30s
Question 1120Question →

Match the following clinical presentations and laboratory profiles with their most likely underlying pathophysiologic diagnosis.

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Items

A 40-year-old woman with central obesity; elevated ACTH, elevated 24-hour urine free cortisol, and suppression of cortisol with high-dose dexamethasone.
A 60-year-old man with hemoptysis; elevated ACTH, elevated 24-hour urine free cortisol, and lack of cortisol suppression with high-dose dexamethasone.
A 35-year-old woman with hypertension; suppressed ACTH, elevated 24-hour urine free cortisol, and lack of cortisol suppression with high-dose dexamethasone.
A 28-year-old woman with fatigue and hyperpigmentation; elevated ACTH, low morning cortisol, and elevated plasma renin activity.

Matches

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Answer

Profile 1 matches Pituitary adenoma; Profile 2 matches Ectopic ACTH; Profile 3 matches Adrenal adenoma; Profile 4 matches Autoimmune adrenalitis.
The diagnosis of adrenal pathology relies heavily on understanding feedback loops. Cortisol exerts negative feedback on pituitary ACTH. If cortisol is high and ACTH is suppressed, the source is primary adrenal overproduction. If both cortisol and ACTH are high, the cause is ACTH-dependent (either central or ectopic). The high-dose dexamethasone test distinguishes between these: it suppresses pituitary sources but not ectopic autonomous sources. Conversely, if cortisol is low and ACTH is high, there is a primary failure of the adrenal gland. Elevated renin confirms the concurrent loss of aldosterone, pointing directly to primary adrenal insufficiency.

Step-by-Step Solution

1
Analyze the first patient presenting with elevated ACTH and cortisol suppression on high-dose dexamethasone.
Identified as Cushing disease (pituitary adenoma).
Pituitary corticotrophs retain partial sensitivity to glucocorticoid negative feedback, distinguishing them from ectopic sources.
2
Analyze the second patient with hemoptysis, elevated ACTH, and no dexamethasone suppression.
Identified as ectopic ACTH syndrome.
Non-pituitary tumors secrete ACTH autonomously and are completely resistant to dexamethasone negative feedback.
3
Analyze the third patient with elevated cortisol but suppressed ACTH.
Identified as primary adrenal adenoma.
An adrenal source of cortisol is ACTH-independent; the high autonomous cortisol levels suppress normal pituitary ACTH release.
4
Analyze the fourth patient with low cortisol, elevated ACTH, and elevated renin.
Identified as primary adrenal insufficiency.
Loss of adrenal tissue impairs both glucocorticoid and mineralocorticoid synthesis, leading to a lack of negative feedback (high ACTH) and volume depletion (high renin).

Key Concept

Hypothalamic-Pituitary-Adrenal Axis Feedback in Endocrine Pathologies
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