Question

To estimate a person's Glomerural Filtration rate, inulin is infused at a steady rate into the blood. After a while, a steady-state plasma concentration is achieved. The inulin concentration in the plasma is .1 g/100ml. A total of 200 ml urine is collected in 2 hours and the inulin concentraion in the urine is 5 g/100ml. What is the GFR or that person. Show your calculations.

Answer 1

GFR approximately equals the inulin clearance rate

So it is given by the formula clearance = UV/P

Where U is urinary concentration of inulin in mg/dl

V is urine flow rate in ml/ min

P is plasma inulin concentration in mg/dl

Here urine is given 200 ml for 2 hrs (means 120 minutes)

Here U and P both are given in gm/ dl ... So no need to convert into mg (of course convertion will also give same values)

So for 1 minute urine flow rate ( V) = 200/120 = 1.66 ml/min

So GFR =( 5 x1. 66) /0.1 = 83.3ml / min

Hope this helps.... Thank you!!!