Acute Kidney Injury USMLE Step 1 Practice Question
A 58-year-old man with sepsis presents with acute kidney injury. Vital signs show BP 92/58 mmHg, HR 118/min, RR 22/min, temperature 39.2°C, and SpO2 98% on room air. Serum creatinine is 3.2 mg/dL (baseline 0.9 mg/dL). Urinalysis shows muddy brown casts without proteinuria. He denies recent nephrotoxin exposure. A researcher administers inulin, a substance freely filtered at the glomerulus that is neither reabsorbed nor secreted anywhere along the nephron. Clearance of this substance most accurately reflects which of the following?
Answer choices
- AFiltration fraction
- BGlomerular filtration rateCorrect answer
- CUrinary concentrating ability
- DEffective renal blood flow
- ERenal plasma flow
- FTubular secretion capacity
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