Creatinine clearance in critically ill surgical patients.

Standard tests of renal function (urine output, BUN, and serum creatinine) were compared with creatinine clearance values and with outcome in 131 critically ill surgical patients. There was a strong negative relationship between creatinine clearance and mortality. Of the 23 patients with a severe reduction of creatinine clearance (less than 20 mL/min), 17 died. In contrast, 23 of the 24 patients with a creatinine clearance of 100 mL/min or more survived. Urine output, BUN, and serum creatinine levels correlated poorly with creatinine clearance. A urine output of less than 30 mL/hr, a BUN level greater than 40 mg/dL, and a serum creatinine level greater than 2.0 mg/dL in all instances were associated with reduced creatinine clearances. However, more than half of all the patients with a normal urine output, BUN, or serum creatinine levels also had a reduced creatinine clearance.