Total plasma clearance of Cr-51-EDTA: Variation with age and sex in normaladults

Although inulin clearance measured during constant infusion is still consid ered the reference method, single-injection of Cr-51-EDTA with subsequent p lasma sampling has become the most popular technique for the routine assess ment of glomerular filtration rate. Despite the fact that the technique has been in use for 30 years, there are only a few reports of normal values ca lculated directly from Cr-51-EDTA data and normal ranges have generally bee n produced by conversions of inulin data. The aim of this study was to meas ure the variation in total plasma clearance, calculated directly from Cr-51 -EDTA measurements, in normal males and females, of Saudi Arabian origin, o ver a wide range. Altogether, 201 potential kidney donors aged 16-60 years were studied. No statistically significant association of total plasma clea rance with age or sex could be demonstrated; however, predictive equations suggesting a small decline in total plasma clearance with age were develope d. The figures presented suggest that the reduction in total plasma clearan ce of Cr-51-EDTA with age is relatively shallow up to the age of at least 6 0 years and that normal ranges produced by conversion of inulin data may ov erestimate the decline with age. ((C) 2000 Lippincott Williams & Wilkins).