Biomedical Engineering: Bridging Medicine and Technology 1st Edition by Veronique Tran,Mark Saltzman

Exercise 17

Inulin is a polysaccharide that happens to be neither secreted nor reabsorbed
by the tubules of the kidney, and its MW (5200 daltons) is low enough to
permit it to pass freely through the glomerulus. It is infused at a steady rate
into the blood of a person whose GFR is to be determined. After a while, a
steady-state plasma concentration is achieved. Assume that blood samples
taken after steady state has been reached show an inulin concentration of 0.1 g/100 mL of plasma. If a total of 180 mL of urine is collected over the next 2 hours, and analysis shows that there is 0.08 g inulin per milliliter in the urine, what is the GFR of the person? It is important to note that inulin is not metabolized by the body and is excreted only in the urine.