Determination of reference intervals for serum creatinine, creatinine excretion and creatinine clearance with an enzymatic and a modified Jaffé method

Objectives: The aim of this study was to determine the reference intervals for serum creatinine, the renal creatinine output and the creatinine clearance (CrCl) with two new methods for accurate creatinine determination. Methods: The reference population consisted of 252 healthy subjects (127 males and 125 females) at the age between 18 and 74 years, median 27. Urine was collected for exactly 24 h. Creatinine in serum and urine was measured with an enzymatic assay (“Creatinine Plus”) and a modification of the kinetic Jaffé reaction, named “Jaffé compensated”. Results: Reference values for serum creatinine were almost identical to previously published ones obtained with the same methods: 0.73–1.18 and 0.55–1.02 mg/dl for males and females, respectively, with the enzymatic, 0.72–1.16 and 0.55–0.96 mg/dl with the compensated Jaffé method (Jcomp). CrCl values were normally distributed and showed no gender difference in contrast to some previous studies. The reference interval for the entire group was found to be 66–143 ml/min with the enzymatic assay and 71–151 ml/min with the chemical one.