Determination of Glomerular Filtration Rate in Advanced Renal Insufficiency

Abstract

The glomerular filtration rate (GFR) has been determined in 17 patients with advanced renal insufficiency (GFR<15 ml/min) by different clearance techniques using creatinine, inulin and ⁵¹Cr-EDTA as filtration markers. With renal inulin clearance as reference method for GFR, endogenous renal creatinine clearance overestimated GFR by an average of 30%. Renal clearance of ⁵¹Cr-EDTA and inulin were closely correlated and thus ⁵¹Cr-EDTA is a suitable GFR marker even at low filtration rates. However, it was found that the plasma clearance of ⁵¹Cr-EDTA overestimated the GFR often by more than 100% in the range 2.6-11.2 ml/min. Renal clearance measured during 24 h was lower than 4 h renal clearance with the patient well hydrated and resting in bed. It is concluded that the precise measurement of low glomerular filtration rates requires the use of renal clearance techniques. Four-hour ⁵¹Cr-EDTA renal clearance is a suitable method for measuring and following the development of renal function in advanced renal insufficiency.