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Renal Plasma Flow RPF is calculated by the clearance of para-aminohippuric acid (PAH), as at low concentrations this compound is completely cleared from the plasma by renal tubular filtration and secretion in a single pass.RPF = C PAH = U PAH V / P PAH

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  • How is para-aminohippuric acid measured?

  • Because the concentration of para-aminohippuric acid in peripheral veins is equal to the concentration in the renal artery, this can be easily sampled along with the clearance of it into the urine in order to estimate renal plasma flow. Renal blood flow is then calculated by dividing renal plasma flow by 1 minus hematocrit.

  • What is renal plasma flow (RPF)?

  • Which in turn leads to: Renal Plasma Flow (RPF) = [PAH] in urine x Urine flow rate / [PAH] in plasma Urine flow rate V 鈥?ml/min or cc/min.

  • What is the relationship between PAH and renal venous blood?

  • Para amino hippuric acid, or PAH, is avidly secreted by the renal tubules so that nearly all of the blood that enters the kidneys is 鈥渃leared鈥?of PAH and renal venous blood contains very little PAH. The amount of PAH appearing in the urine per unit time, then, is equal to the amount contained in the blood that perfuses the kidney per unit time.

  • What is the formula for renal plasma flow in urine?

  • RPF x [PAH] in plasma = [PAH] in urine x Urine flow rate. Which in turn leads to: Renal Plasma Flow (RPF) = [PAH] in urine x Urine flow rate / [PAH] in plasma. With: Renal Plasma Flow – ml/min or cc/min; [PAH] in urine or in plasma 鈥?in mg/ml;