Renal System MCAT Practice Question
A 58-year-old man with a 10-year history of hypertension and type 2 diabetes mellitus is started on lisinopril for blood pressure control and renal protection. After 3 months of therapy, his laboratory values show a serum creatinine increase from 1.0 to 1.3 mg/dL (estimated GFR decrease from 85 to 62 mL/min/1.73m²) and urine protein-to-creatinine ratio decrease from 1.2 to 0.4 g/g. His blood pressure is well-controlled at 128/78 mmHg. Which of the following best explains the reduction in proteinuria despite the decline in glomerular filtration rate?
Answer choices
- AIncreased afferent arteriolar resistance and decreased glomerular capillary hydrostatic pressureCorrect answer
- BDecreased efferent arteriolar resistance and increased glomerular capillary hydrostatic pressure
- CEnhanced proximal tubule reabsorption of filtered proteins via megalin-mediated endocytosis
- DSelective expansion of the glomerular basement membrane charge barrier
- EDecreased plasma oncotic pressure promoting increased tubular reabsorption
- FIncreased mesangial cell contraction reducing effective filtration surface area
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