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Updated: Nov 19, 2025

Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat
Published on: July 26, 2015
A plasma creatinine- and urea-based equation to estimate glomerular filtration rate in rats
Paul J Besseling1, Tobias T Pieters1, Isabel T N Nguyen1
1Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands.
Abstract:
Monitoring renal function is a vital part of kidney research involving rats. The laborious measurement of glomerular filtration rate (GFR) with administration of exogenous filtration markers does not easily allow serial measurements. Using an in-house database of inulin clearances, we developed and validated a plasma creatinine- and plasma urea-based equation to estimate GFR in a large cohort of male rats [development cohort n = 325, R2 = 0.816, percentage of predictions that fell within 30% of the true value (P30) = 76%] that had high accuracy in the validation cohort (n = 116 rats, R2 = 0.935, P30 = 79%). The equation was less accurate in rats with nonsteady-state creatinine, in which the equation should therefore not be used. In conclusion, applying this equation facilitates easy and repeatable estimates of GFR in rats.NEW & NOTEWORTHY This is the first equation, that we know of, which estimates glomerular filtration rate in rats based on a single measurement of body weight, plasma creatinine, and plasma urea.
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