A determination of the \"filtration fraction\" is an important clinical measurem

Question

A determination of the "filtration fraction" is an important clinical measurement, which is a determination of the fraction of the renal plasma flow that is represented in the ultrafiltrate of the glomeruli. A normal filtration fraction is approximately 20%. A) Calculate the filtration fraction for this patient suffering from renal artery stenosis from the following data. (15 points) B) Explain why the filtration fraction in this patient deviates from normal (5 points) Plasma Inulin-1.25 mg% Plasma PAH-1.5 mg% [Urine Inulin-150 mg% Urine PAH-500 mg% Urine Output - 1.5 L/day

Explanation / Answer

Q.A. Answer: Filtration fraction = 36%

Solution :- We know,

Clearance of Inulin= GFR,

Clearance of PAH(para amino hippuric acid)=RPF.

So, From given data

Plasma Inulin= 1.25mg%, Plasma PAH=1.5mg%

Urine Inulin=150mg%, Urine PAH=500mg%.

GFR= Urine inulin / plasma inulin

= 150/1.25 =120mg

RPF= Urine PAH/ Plasma PAH

=500/1.5 = 333mg

We know that, Filtration Fraction(FF)= (GFR/RPF)*100

=(120/333)*100 = 36%

Q.B. Answer :

This filtration fraction gets deviated due to the change in the PAH And Inulin concentration. this PAH and Inulin bot helps in stability of hypertension. But in a condition like Artery Stenosis which is also known as Heyperhomocysteinemia or H type heypertension the PAH and Inulin levels get diverted from the normal level which in turn changes the Filtration Fraction from the normal range(20%).

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