[Variations according to age and gender for creatinine clearance estimated with the Cockroft and Gault formula in a selected population of ambulatory adults].

The distribution and variations according to age and gender for the creatinine clearance calculated by the Cockcroft and Gault formula (Cl C-G) were determined thanks to a case-control study on a population of selected adults with a plasma creatinine concentration < 137 micromol/L (man) or < 104 micromol/L (woman) and a plasma urea concentration < 8.3 mmol/L. 286 men and 270 women aged between 18 and 80 were considered. The frequency distributions for creatinine (dosed by a kinetic Jaffe method ) and Cl C-G are Gaussian (p < 0.01; Kolmogorov-Smirnov test). Cl C-G diminishes with age (r = 0.73; p < 0.001), average: 10 mL/min/decade (man) and 11 mL/min/decade (woman). No significant relation could be found between the weight/creatininaemia ratio and age. Cl C-G is weaker for women: 11 to 18 mL/min according to age. 53% of women older than 70 years have an estimated glomerular filtration rate below 60 mL/min. The 2.5th centiles for Cl C-G values vary, for man: from 105 mL/min (confidence interval 95%: 100-110 mL/min) between 18 and 30 years old, to 53 mL/min (49-57) between 71 and 80 years old; for woman: from 85 mL/min (80-90) between 18 and 30 years old to 42 mL/min (38-46) between 71 and 80 years old. With such results, the correcting factor related to Cockcroft and Gault's formula gender seems to be insufficient. New reference values and limits of decision of Cl C-G must be determined for each analytical method.