Glomerular filtration rate and creatinine production in adult icteric patients

Various methods for serum creatinine determination were compared and validity of the Cockroft-Gault algorithm for calculating creatinine clearance was tested in adult icteric patients. Using conventional Jaffé assays, negative interference is proportional to the serum bilirubin content. Pretreatment of the serum with bilirubin oxidase was more efficient in eliminating bilirubin than pretreatment with potassium ferricyanide. Due to a continued creatine-poor diet and liver dysfunction, erythrocyte creatine levels and creatinine output rate were decreased. Median effect (creatinine equivalent) of non-specific chromogens in the unmodified Jaffé assay was 21 mumol/l (range: 1-108 mumol/l), vs. 19 mumol/l (range: 16-26 mumol/l) for the reference population. In the absence of multi-organ failure, the Cockroft-Gault algorithm could be used for estimating glomerular filtration rate. In patients with multiple organ failure however, we recommend correction for both bilirubin and non-specific chromogens for measuring the serum creatinine concentration.