Introduction

• Presence of myoglobin (muscle pigment) in the urine.
• Cause: myoglobin released from muscle during severe muscle necrosis or trauma.
• Signs: brownish red urine.
• Diagnosis: positive occult blood reaction; no erythrocytes in urine sediment.
• Treatment: treat primary cause of muscle damage, fluid therapy Fluid therapy to support renal function.
• Prognosis: depends on severity of muscle damage.

Pathogenesis

Etiology

• Myoglobin released from muscle following:
  • Extensive crushing injuries to muscle.
  • Exertional rhabdomyolysis ("Greyhound cramps"; "Azoturia").
  • Hyperthermia.
  • Rarely seen in acute polymyositis.
  • Rarely seen associated with degenerative myopathies.
  • Snake envenomation Adder bite poisoning.

Predisposing factors

• Muscle damage.

Pathophysiology

• Myoglobin enters urine following muscle trauma or necrosis.

• Myoglobin released from damaged or necrotic muscle → binds to plasma proteins → excreted in urine before reaching levels that would discolor plasma.
• Myoglobin is extremely toxic to renal tubules, and myoglobinuria may result in acute renal failure Kidney: acute kidney injury (AKI).

Timecourse

• Often acute.

Diagnosis

Treatment

Outcomes