Renal plasma flow is best determined by (LQ)
I. Renal plasma flow - RPF
a. Can be measured by infusing para-amino hippuric acid (PAH) and determining its urine and plasma concentration.
b. 90% of the PAH in arterial blood is removed in a single circulation through the kidney. It is therefore become common place to calculate the “renal plasma flow” by dividing the amount of PAH in urine by the plasma PAH level.
c. Effective renal plasma flow (ERPF): -
ERPF = UPAH X V = Clearance of PAH
= 625 ml/min.
d. Actual - RPF = ERPF = 630
Extraction ratio 0.9
= 720 mI/min.
II. Renal Blood flow -
= RPF x 1
= 700 X 1
= 1273 ml/mm.
III. “for determination of the GFRdo a creatinine or Inulin clearance test and for determination of RBF or RPF the PAH clearance is to be done”