Effective renal plasma flow

Effective renal plasma flow (eRPF) is a measure used in renal physiology[1] to calculate renal plasma flow (RPF) and hence estimate renal function.

"eRPF" redirects here. For the river in Baden-Württemberg, Germany, see Erpf (river).
Parameter Value
renal blood flow RBF = 1000 mL/min
hematocrit HCT = 40%
glomerular filtration rate GFR = 120 mL/min
renal plasma flow RPF = 600 mL/min
filtration fraction FF = 20%
urine flow rate V = 1 mL/min
Sodium Inulin Creatinine PAH
SNa = 150 mEq/L SIn = 1 mg/mL SCr = 0.01 mg/mL SPAH =
UNa = 710 mEq/L UIn = 150 mg/mL UCr = 1.25 mg/mL UPAH =
CNa = 5 mL/min CIn = 150 mL/min CCr = 125 mL/min CPAH = 420 mL/min
ER = 90%
ERPF = 540 mL/min

Because the extraction ratio of PAH is high, it has become commonplace to estimate the RPF by dividing the amount of PAH in the urine by the plasma PAH level, ignoring the level in renal venous blood. The value obtained in this way is called the effective renal plasma flow (eRPF) to indicate that the level in renal venous plasma was not measured.[2]: 664–665 

The actual RPF can be calculated from eRPF as follows:

where extraction ratio is the ratio of compound entering the kidney that is excreted into the final urine.[2]: 664–665 

When using a compound with an extraction ratio near 1, such as para-aminohippurate (PAH), eRPF approximates RPF. Therefore, PAH clearance can be used to estimate RPF.[3]

References
  1. "Hubio562: Clearance Lab Answers". Archived from the original on September 12, 2006. Retrieved 2009-04-29.
  2. Barrett, Kim E. (2019). Ganong's review of medical physiology. Susan M. Barman, Heddwen L. Brooks, Jason X.-J. Yuan (26 ed.). New York. ISBN 978-1-260-12241-1. OCLC 1250311968.{{cite book}}: CS1 maint: location missing publisher (link)
  3. Costanzo, Linda (2012). Physiology Cases and Problems. Lippincott Williams & Wilkins. p. 165. ISBN 9781451120615. Retrieved 1 November 2018.
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