Low molecular weight proteinuria in association with paroxysmal myoglobinuria

A patient with paroxysmal myoglobinuria presented with low molecular weight (LMW) proteinuria in association with an episode of exertional myoglobinuria. Since no signs of acute renal failure were present, the cause was probably competition between myoglobin and other LMW proteins for proximal tubular reabsorption. Agarose gel electrophoresis was found to be an excellent method for the investigation of myoglobinuria since this technique not only allowed the separation of myoglobin from hemoglobin but also myoglobin from metmyoglobin.