Variables affecting creatinine clearance prediction.

Patient data were analyzed retrospectively to evaluate the relationship between several body-weight variables and creatinine production and clearance. Data from 722 creatinine clearance determinations in 627 patients older than 12 years were analyzed. Weight variables were actual body weight (ABW), lean body weight (LBW), ideal body weight (IBW), and lean body mass (LBM). Weight-independent and weight-dependent clearance prediction methods were evaluated. Actual creatinine clearance values were compared with these predictions. Use of LBW and IBW produced equivalent estimates of creatinine clearance that were closer to measured values than those obtained with ABW. The use of LBW or IBW was not appropriate in patients less than 60 inches tall nor in morbidly obese patients. Weight-dependent clearance estimation was superior to weight-independent predictions in morbidly obese patients. A new LBM-based clearance estimation formula was derived; it may be useful for patients less than 60 inches tall. The use of LBM, particularly in patients less than 60 inches tall, should be investigated further.