Internal Medicine Exam Nephrology and Kidney Injury 4

Question 1

A 60-year-old man with gout and CKD has a serum uric acid of 11 mg/dL. He starts allopurinol and develops a severe desquamating rash with hepatitis. Which HLA allele is strongly associated with allopurinol hypersensitivity syndrome?

Accepted Answer

HLA-B*58:01

Answer

HLA-B*58:01 is strongly associated with allopurinol-induced severe cutaneous adverse reactions, particularly in patients of Asian descent.

Question 2

A 45-year-old HIV-positive man on tenofovir develops proximal tubular dysfunction with glucosuria (normal serum glucose), phosphaturia, and aminoaciduria. What syndrome does this represent?

Accepted Answer

Fanconi syndrome

Answer

Tenofovir causes mitochondrial toxicity in proximal tubules, leading to Fanconi syndrome with generalized proximal tubular dysfunction.

Question 3

A 55-year-old woman develops oliguric AKI after prolonged hypotension during cardiac surgery. Urine microscopy shows muddy-brown granular casts. Urine sodium is 55 mEq/L and FENa is 3.2%. What is the mechanism?

Accepted Answer

Ischemic acute tubular necrosis

Answer

Ischemic ATN follows prolonged hypoperfusion, manifesting as muddy-brown granular casts, high urine sodium (>40 mEq/L), and FENa >1% due to tubular injury.

Question 4

A 38-year-old woman with hypertension refractory to three medications has a serum potassium of 2.8 mEq/L and metabolic alkalosis. Aldosterone-to-renin ratio is 40 (ng/dL)/(ng/mL/hr). CT shows a 1.8 cm left adrenal adenoma. What is the best next step?

Accepted Answer

Perform adrenal vein sampling

Answer

Adrenal vein sampling is required before surgery to confirm unilateral aldosterone hypersecretion, as CT can miss contralateral disease or misidentify non-functioning adenomas.

Question 5

A 30-year-old man with no past history develops cola-colored urine, periorbital edema, and hypertension 3 weeks after a streptococcal pharyngitis. C3 is low, C4 is normal. Renal biopsy would most likely show:

Accepted Answer

Subepithelial (humps) deposits on electron microscopy

Answer

Post-streptococcal GN shows subepithelial hump-shaped deposits on electron microscopy and granular IgG/C3 on immunofluorescence, with selective C3 consumption.

Internal Medicine Exam Practice Test

Internal Medicine Exam Practice Test

Internal Medicine Exam Nephrology and Kidney Injury 4