Elevations of hemopexin levels in neuromuscular disease

Hemopexin, a serum glycoprotein that binds free heme and transports it to hepatic parenchymal cells, has been measured by radial immunodiffusion. We have confirmed elevation of serum hemopexin concentration in Duchenne's muscular dystrophy patients and carries, and demonstrated elevations in dermatomyositis/polymyositis and myasthenia gravis, but not in amyotrophic lateral sclerosis. In monkeys, elevations of hemopexin levels were specifically induced by hematin injections, muscle-crush, or myoglobin injections. Myoglobin leakage is the likely explanation of hemopexin level elevation in Duchenne's dystrophy patients and carriers and in dermatomyositis/polymyositis. In myasthenia gravis there might be a slight myoglobin leakage not heretofore suspected; or, the elevation of hemopexin levels might be a new reflection of a dysimmune state in myasthenia gravis, and perhaps as such is a further incrementing factor in dermatomyositis/polymyositis. Hemopexin, presumably as a longer-phase reactant, is sometimes an index of neuromuscular disease when other data are negative or equivocal.