Myoglobinuria

Myoglobinuria describes the presence of myoglobin (a muscle protein) in the urine .

Myoglobin is released if there is muscle injury or necrosis (rhabdomyolysis).

Causes of myoglobinuria include:

• trauma
• electrocution
• ischaemia
• immobility
• excessive exercise
• myositis
• drugs e.g. statins, fibrates
• toxins e.g. snake bite, carbon monoxide, alcohol, ecstasy
• inherited muscle disorders e.g. McArdle's disease
• malignant hyperpyrexia
• neuroleptic malignant syndrome
• metabolic causes e.g. hypokalaemia, hypophosphataemia
• coma

Clinical features:

• may be asymptomatic - depending on cause
• non-specific symptoms e.g. muscle tenderness, pain or swelling

Investigations:

• dipstick urine - positive for blood but negative for red blood cells on microscopy
• blood tests - increased creatinine, increased urea, increased potassium, reduced calcium, increased phosphate, increased urate, increased CK, increased LDH