Myoglobinemia and myoglobinuria in patients with myositis

Twelve of 23 patients with dermatomyositis or polymyositis demonstrated myoglobin in their serum or urine in concentrations of 0.005–3.280 mg/ml. This was detected by means of a specific immunologic assay. Myoglobin was more frequently noted in serum than urine. The frequency of appearance of myoglobin in these patients was not related to age or sex, but was more common among those with dermatomyositis (11 of 18) than polymyositis (1 of 5). Serum enzyme values (SGOT, CPK, LDH) were slightly higher in the group with myoglobinemia than in those without, but there was considerable overlap. Myoglobin was found in most patients with myositis before steroid therapy was begun (12 of 19), and its presence was associated with renal failure in two patients.