renal equations

Question 1

what is the equation for filtration fraction?

Answer 1

FF = GFR/RPF

RPF = renal blood flow * (1-hematocrit)

Question 2

if 1 out of every 5 liters of plasma enters bowmans space and the the pt has a GFR of 0.1 L/min, with a hematocrit of 0.5. What was the renal plasma flow?

Answer 2

RPF=GFR/FF

FF = the fraction of PLASMA that flows through the glomeruli that is filtered accross the glomerular caillaries into Bowman’s space

Question 3

What is the renal blood flow if hematocrit is 50% and urine flow is 1ml/min?

                       Urine                         Serum inulin                        200                           2 glucose                     0                             80 potassium                50                             5 uric acid                   15                              3 PAH                        100                             0.2

Answer 3

need to know that renal plasma flow = PAH clearance
and that renal blood flow = PAH clearance/ (1-hematocrit)

PAH clearance = U([PAH] V (urine flow)/ P[PAH]
= (1001)/.2 = RPF
(100*1/.2)/(1-.5) = RBF = 1000