A patient has a GFR of 120 mL/min and an effective renal plasma flow of 600 mL/min (from PAH clearance). What is the filtration fraction?
Answer and explanation
Correct answer: D. 20%
- Step 1: Filtration fraction = GFR / renal plasma flow. Step 2. 120 / 600 = 0.20. Answer: 20%. Why not the others: 5% inverts the ratio, and 50% and 80% are not produced by these numbers. A normal filtration fraction is about 20%.
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