Serum creatinine in patients with spinal cord injury.

In a group of 18 male patients with spinal cord injury, we found serum creatinine to be within normal limits or only minimally elevated despite significant reduction in creatinine clearance. In 8 control subjects with serum creatinine between 1.0 and 1.5 mg/dL (88.4 and 132.6 mumol/L), the measured creatinine clearance was 66.4 +/- 28.2 mL/min. In contrast, in the 5 patients with spinal cord injury whose serum creatinine was in the same range, the measured creatinine clearance was only 31.0 +/- 19 mL/min. Urinary creatinine excretion was lower in patients with spinal cord injury than in the 18 male controls (653 mg/24 hr vs. 1505 mg/24 hr). The decreased urinary creatinine could not be explained by differences in age, sex, or body weight. We calculated the relationship of creatinine clearance (Ccr) and serum creatinine (Scr) in patients with spinal cord injury to be given by the equation Ccr (mL/min) = 45/Scr (mg/dL), r = 0.73. We recommend timed urine collections for creatinine to estimate creatinine clearance accurately for clinical evaluation of patients with spinal cord injury.