A prospective study of urine and serum myoglobin levels in patients with acute rhabdomyolysis.

Serum and urine myoglobin levels, measured by radioimmunoassay, were determined prospectively in eight patients with acute rhabdomyolysis, within 24 hours of admission. Five patients had urine myoglobin concentrations greater than 1,000 ng/ml (normal < 5 ng/ml); four of these patients subsequently developed acute renal failure. In three patients whose urinary myoglobin levels ranged from 19 to 275 ng/ml, acute renal failure did not occur. This difference in the occurrence of acute renal failure between the two patient groups was statistically significant (p < 0.05). Mean peak serum creatinine was significantly higher in the patients with high urine myoglobin (6.4 +/- 1.3 mg/dl) compared to those with low urine myoglobin (2.2 +/- 0.3 mg/dl), p < 0.02. There was no statistical correlation between level of serum creatine phosphokinase and serum or urine myoglobin, although the serum and urine myoglobin levels correlated well with each other. These findings suggests that among other factors, urine myoglobin may need to reach a critical level in order for myoglobinuric renal failure to ensue.