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Calculate the renal plasma flow of a pt given the data below:
Effective Renal Plasma Flow ........... 585 ml/min
Uncorrected measured Hct ............. 45%
Renal Extraction of PAH ................. 0.90
(i.e. 90% of PAH is removed from the plasma by the kidney in a single passage)
A- 1064 ml/min
B- 961 ml/min
C- 1066 ml/min
D- 650 ml/min
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Do u know why they call it "EFFECTIVE Renal Plasma Flow" rather than "Renal Plasma Flow" in case of PAH Clearance ?
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D..
effetive plasma flow=RPF*extraction rate
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It is called ERPF in case of PAH because
(1) plasma flow through renal connective and adipose tissue is not included and (2) incomplete extraction of solutes from rapidly flowing blood in peritubular capillaries precludes total secretion of all the PAH present in the blood perfusing the tubules.
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EFFECTIVE Renal Plasma Flow is almost close to the RPF
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yes
At Low Plasma PAH concentration:
-90% (not 100%) of the true Renal Plasma Flow get cleared off PAH (PAH removed).
cz remaining 10% of the Renal Plasma Flow perfuses (goes to) the "Renal CAPSULE" ...so no opportunity to remove PAH from that plasma Flow.
hence Clearance of PAH will equal only 90% of Renal Plasma Flow said to be "Effective Renal Plasma Flow"
"D" is correct.
we can simply use the formula mentioned by maryam.
Effective RPF = RPF * Extraction rate(clearance)
RPF = Effective RPF / Extraction rate(clearance)
RPF = 585 / 0.9
RPF = 650 ml/min
*IF
Renal Extraction of PAH ................. 1.0 (assume)(100% removed)
RPF = Effective RPF / Extraction rate(clearance)
RPF = 585 / 1.0
RPF = 585 ml/min (same as the Effective RPF)
