Reference data for 51Cr-EDTA measurements of GFR derived from live kidney donors

Abstract

Background: 51Cr-EDTA is widely used to measure glomerular filtration rate (GFR) for the assessment of renal function. Aim: To assess the dependence of GFR on age and gender and produce reference data for the interpretation of 51Cr-EDTA GFR measurements in adults. Methods: Retrospective study of 428 subjects (218 F, 210 M, aged 19 to 72 years) undergoing assessment as live kidney donors. GFR was evaluated from 51Cr-EDTA plasma clearance using blood samples taken at 2, 3 and 4 h. The slope–intercept GFR was corrected for body surface area (Du Bois equation) and for the fast exponential (Brochner–Mortensen method). The data were analysed for the dependence on age and gender using multi-variant regression analysis. Precision was evaluated from duplicate measurements in 22 subjects. Results: For 187 subjects aged 19 to 40 years the dependence of GFR on age was not statistically significant (P=0.59). Mean GFR was 105.9 ml·min−1 with a root mean standard error (RMSE) of 16.4 ml·min−1. GFR was 2.4 ml·min−1 higher in women than men (P=0.35, not significant). In 241 subjects aged 40 to 73 years GFR decreased by 0.94 ml·min−1year−1 (standard error 0.07 ml·min−1year−1) in both sexes with an RMSE of 14.4 ml·min−1.Over the whole age range GFR was 2.8 ml·min−1 higher in women than men (P=0.06). For the 22 subjects with duplicate measurements the precision was 7.5 ml·min−1.