USMLE Forum - Largest USMLE Community

Research studies are conducted on Drug X. It is freely filtered in the glomeruli and reabsorbed in the renal tubules. As part of the study, drug X is received by a healthy volunteer. The following data are then obtained:

Inulin Clearance = 100 mL/min
PAH Clearance = 500 mL/min
Plasma concentration of Drug X = 0.5 mg/mL
Tubular reabsorption of Drug X = 25 mg/min

What is the excretion rate for Drug X in the volunteer who received it?
A. 100 mg/min
B. 75 mg/min
C. 50 mg/min
D. 25 mg/min
E. 0 mg/min

Please include an explanation to your answer. Thanks.

D.

Explain, por favor

to solve this q',use inuline(not PAH) so 100 * .5 = 50
then subtract 25 tubular reabsorption.
--> 50-25 = 25 (D)

oops!

(*Inulin Clearance = 100 mL/min) X (Plasma concentration of Drug X = 0.5 mg/mL) - Tubular reabsorption of Drug X = 25 mg/min ->

"excretion rate for Drug X" ?= 25 mg/min

*Freely filtered, not reabsorbed or secreted.

Disculpa
Always 78sec get to me.

"D" is correct and well-explained

Inulin clearance represents filtration rate.
PAH clearance represents Renal plasma flow.

Thank you, cardio and tictoc

Thank you for Q.

Thank you too

I think I had a similar Q in UW and I was so proud when I got it right.
Thanks