ABIM Test 2 — Questions and Answers
Question 1: A 58-year-old man with type 2 diabetes presents with a serum creatinine of 2.1 mg/dL (baseline 1.0) after starting an NSAID for knee pain two weeks ago. Which mechanism best explains this acute kidney injury?
- Allergic interstitial nephritis
- Inhibition of prostaglandin-mediated afferent arteriolar dilation (Correct answer)
- Direct tubular toxicity
- Renal vein thrombosis
Correct answer: Inhibition of prostaglandin-mediated afferent arteriolar dilation
NSAIDs inhibit prostaglandin synthesis, reducing afferent arteriolar dilation that is critical for maintaining GFR in states of low effective circulating volume (as in diabetic nephropathy).
Question 2: A 45-year-old woman with Graves' disease is started on methimazole. Six weeks later she develops a fever, sore throat, and absolute neutrophil count of 200/µL. What is the most appropriate next step?
- Reduce methimazole dose by 50%
- Switch to propylthiouracil
- Discontinue methimazole immediately and initiate G-CSF (Correct answer)
- Add prophylactic antibiotics and continue methimazole
Correct answer: Discontinue methimazole immediately and initiate G-CSF
Agranulocytosis is a rare but life-threatening complication of methimazole; the drug must be stopped immediately, and G-CSF may be used to accelerate neutrophil recovery.
Question 3: A 72-year-old woman is hospitalized for pneumonia. On day 3 she develops a maculopapular rash, eosinophilia, and rising creatinine. Urinalysis shows WBC casts and eosinophiluria. Which diagnosis is most likely?
- Post-infectious glomerulonephritis
- Contrast nephropathy
- Acute interstitial nephritis (Correct answer)
- Minimal change disease
Correct answer: Acute interstitial nephritis
The triad of rash, eosinophilia, and eosinophiluria with WBC casts after antibiotic exposure is classic for acute interstitial nephritis.
Question 4: A 55-year-old man with heart failure (EF 30%) is found to have a potassium of 3.0 mEq/L. He is on lisinopril, carvedilol, and furosemide. Which potassium-sparing intervention has demonstrated a mortality benefit in this population?
- Oral potassium chloride supplementation
- Spironolactone (Correct answer)
- Amiloride
- Triamterene
Correct answer: Spironolactone
Spironolactone (and eplerenone) are aldosterone antagonists shown in RALES and EPHESUS trials to reduce mortality in heart failure with reduced ejection fraction.
Question 5: A 38-year-old woman presents with episodic severe headache, diaphoresis, and palpitations. Her blood pressure during an episode is 210/120 mmHg. 24-hour urine metanephrines are markedly elevated. Which antihypertensive should be initiated first?
- Metoprolol
- Lisinopril
- Phenoxybenzamine (Correct answer)
- Hydrochlorothiazide
Correct answer: Phenoxybenzamine
Alpha-blockade with phenoxybenzamine must be established before beta-blockade in pheochromocytoma to prevent unopposed alpha-mediated hypertensive crisis.
Question 6: A 62-year-old man is found to have a 3-cm solid pulmonary nodule on CT. PET scan shows no FDG uptake. Bronchoscopy is non-diagnostic. What is the most appropriate next step according to evidence-based guidelines?
- Observation with repeat CT in 12 months
- CT-guided needle biopsy
- Video-assisted thoracoscopic surgery (VATS) resection (Correct answer)
- Empiric radiation therapy
Correct answer: Video-assisted thoracoscopic surgery (VATS) resection
A solid nodule ≥3 cm with a non-diagnostic bronchoscopy warrants surgical resection (VATS) because malignancy risk is high regardless of PET negativity.
Question 7: A 50-year-old woman with primary biliary cholangitis presents with fatigue, pruritus, and elevated alkaline phosphatase. Which therapy is first-line and has been shown to slow disease progression?
- Colchicine
- Ursodeoxycholic acid (Correct answer)
- Methotrexate
- Prednisone
Correct answer: Ursodeoxycholic acid
Ursodeoxycholic acid (UDCA) improves liver biochemistry, delays histologic progression, and improves transplant-free survival in primary biliary cholangitis.
ABIM Test 2
A 58-year-old man with type 2 diabetes presents with a serum creatinine of 2.1 mg/dL (baseline 1.0) after starting an NSAID for knee pain two weeks ago.
Which mechanism best explains this acute kidney injury?