A patient has a glomerular filtration rate of 120 mL/min and renal plasma flow of 600 mL/min. What is his filtration fraction?
- A 50 percent
- B 40 percent
- C 20 percent ✓
- D 10 percent
Correct answer: C. 20 percent
Explanation
Filtration fraction equals GFR divided by renal plasma flow: 120/600 = 0.20, or 20 percent. The normal value lies between 15 and 20 percent, so 20 percent fits this patient. The distractor of 10 percent would result if renal plasma flow were mistakenly taken as total renal blood flow, which is roughly twice the plasma flow because the hematocrit occupies about half of blood volume.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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