Depletion of serum hemopexin in fulminant rhabdomyolysis. Evidence for an interaction of hemopexin with myoglobin-derived heme.

Hemopexin is a normal serum glycoprotein that functions as a carrier for intravascularly liberated free heme. Although its role is well established in the reutilization of hemoglobin-derived heme, there have been no previous clinical data to support its suspected interaction with heme released in the degradation of myoglobin. In a patient with fulminant rhabdomyolysis, we found depletion of serum hemopexin in the presence of high serum levels of myoglobin with normal levels of haptoglobin and hemoglobin. This combination of laboratory findings is evidence for an interaction between myoglobin-derived heme and hemopexin and implies a role for hemopexin in the catabolism of myoglobin. These findings support the proposed induction mechanism for observed increases of serum hemopexin in Duchenne muscular dystrophy and in polymyositis.