renal problem/question

[md90]

22 year-old woman participating in a study that measures renal function; Evaluation of serum and urine shows the following:
Serum Urine
Sodium 140 100
Potassium 4 50
Glucose 100 0
Creatinine 1 100
p-Aminohippuric acid 0.1 50

Assuming a urine flow of 1ml/min, what is the filtration fraction?

A. 0.10
B. 0.20
C. 0.30
D. 0.40
E. 0.50


I need help in solving this problem.. here is what I have:

Filtration fraction=GFR/RBF, where creatinine Clearance is an approximate measure of GFR; RBF=RPF/1-Hct; p-Aminohippuric acid is PAH; RPF=PAH=0.1; But don't we need the Hct?

I would greatly appreciate anyone in the forum to explain this problem to me... thank you.

[dr41]

md90 I think there is one mistake here.
FF is NOT GFR/RBF
but
FF is GFR/RPF (Renal PLASMA flow and not Renal blood flow).
So we do not need Hct to calculate GFR. I hope it helps.

[dr41]

And FF calculated will be 0.2 Ans B
Please correct me if I am wrong.

[md90]

yes.. I came to the same conclusion AFTER removing myself, taking a nap and having dinner... plus I peeked at the formula; thank you so much, dr41!!! I also came with 0.2 (answer b)