Myoglobinuria as a manifestation of rhabdomyolysis following extreme physical exertion

Overview

Myoglobinuria refers to higher than normal physiological concentrations of myoglobin in the urine, usually causing a dark red discoloration. Due to its small molecular weight, myoglobin is readily excreted in the urine during rhabdomyolysis. In acidic urine myoglobin reacts with Tamm-Horsfall proteins which can bind to the surface of the tubular cells causing damage. Myoglobinuria is the external manifestation of rhabdomyolysis, a syndrome characterized by necrosis of striated muscle cells and release of their content into the circulatory system. The severity of the disease can vary in form from asymptomatic to life-threatening with acute renal failure and electrolyte imbalances. Basic treatment and prevention of kidney damage involves early and aggressive volumexpansion, induction of massive diuresis and alkalinisation of urine. Acute episodes of rhabdomyolysis induced by physical exertion may be a manifestation of a heterogeneous group of inherited or acquired diseases. We present a case study of 2 young men referred to our department with presumed macroscopic haematuria based on red dyscologation of the urine as well as the presence of hemoglobin in the urine which was determined by a urine test strip. Laboratory-confirmed significant rhabdomyolysis with myoglobinuria required hospitalization for renoprotective treatment. When examining young and otherwise healthy individuals for hematuria, myoglobinuria has to be considered in the differential diagnosis and the patient should be asked specifically about prior physical exertion. It is necessary to supplement the history with an examination of urine sediment which will show a large discrepancy between red discoloration of the urine and a low number of erythrocytes in the sediment. Laboratory blood testing will show significant elevation of serum myoglobin and creatinkinase. This case study should serve as a reminder that myoglobinuria is a possible cause of red urine discoloration in patients referred to urological care.

Key words:
acute renal failure, haematuria, myoglobinuria, rhabdomyolysis.