REPRODUCIBILITY OF SIMPLIFIED TECHNIQUES FOR THE MEASUREMENT OF CR-51-EDTA CLEARANCE

The aim of this study was to assess the reproducibility of a number of simplified clearance methods using chromium-51 ethylenediamine tetraa cetic acid (Cr-51-EDTA) and to compare these with the multiple blood s ample technique. Twenty-four healthy volunteers were enrolled into the study. The test was performed twice, 1 week apart and under similar p hysiological conditions. After intravenous injection of the tracer, 13 blood samples were taken between 5 and 240 min. The reference clearan ce was calculated after adapting a bi-exponential fit on the whole pla sma disappearance curve. Simplified methods included the slope interce pt method using different combinations of blood samples (2 and 4 h; 2, 3 and 4 h; 1.5, 2, 3 and 4 h; 1.5, 2 and 3 h) and several single clea rance methods Constable 3 h; Groth 3 h; Groth 4 h). The standard devia tion of the differences between the first and second measurements were similar for all methods, confirming the comparable reproducibility of these methods.