Renal Physiology · NEET PG Preparation Physiology
In a classic clearance study, a patient's glomerular filtration rate (GFR) is measured using inulin, and effective renal plasma flow (ERPF) is measur…
Practice question from Renal Physiology (NEET PG Preparation Physiology), with the correct answer and a step-by-step solution.
hard · MCQ · Q-BDF6EC
In a classic clearance study, a patient's glomerular filtration rate (GFR) is measured using inulin, and effective renal plasma flow (ERPF) is measured using para-aminohippuric acid (PAH). If the hematocrit is 40%, which of the following represents the correct method to calculate true total renal blood flow (RBF)?
- A.ERPF divided by (1 - Hematocrit)Correct answer
- B.ERPF multiplied by (1 - Hematocrit)
- C.Inulin clearance divided by (1 - Hematocrit)
- D.PAH clearance multiplied by the extraction ratio of PAH
Solution
Effective renal plasma flow (ERPF) is estimated by the clearance of PAH. Renal plasma flow (RPF) is equal to ERPF divided by the extraction ratio of PAH (which is normally about 0.9, but if ERPF is used assuming complete extraction, RPF = ERPF / 0.9, though often simplified in clinical questions). Total Renal Blood Flow (RBF) is calculated from RPF by dividing by (1 - Hematocrit) to account for the cellular fraction of blood: .
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