Lack of evidence that formula-derived creatinine clearance approximates glomerular filtration rate in pediatric intensive care population.

During the four-year period from January 1980 to April 1984, 56 patients were admitted to the Pediatric Intensive Care Unit (PICU) whose care required timed urine collections using indwelling urinary catheters. The glomerular filtration rate derived from the clearance of endogenous creatinine with accurate timed urine volume is compared to that derived from the formula, 0.55 body length (cm)/plasma creatinine (mg/dl). There is a significant difference in the results between the two methods, p less than 0.0001. The largest divergence arises in those with creatinine clearance of less than 40 ml/min per 1.73 sq.m. In this subgroup, the formula derived glomerular filtration rates consistently overestimate the renal function and create a misleading assurance of minimal renal impairment. Therefore, our findings suggest that the latter formula is not applicable to PICU patients for consideration of fluid and electrolyte balance, administration of nephrotoxic drugs or criteria for dialysis.