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HeikkiSaha

Rhabdomyolysis

Essentials

  • Suspect rhabdomyolysis in patients with typical history (particularly those found unconscious), symptoms and clinical findings.
  • When suspicion arises diagnosis is easy to verify (serum creatine kinase, CK).
  • Intensified fluid therapy is the most essential treatment measure: start with infusing 1 000 ml of 0.9% saline solution during the first hour.

Definition

  • Rhabdomyolysis refers to an injury of striated muscle. It may result in acute renal failure unless treatment is instigated early enough.

Aetiology

Signs and symptoms

  • The affected area (limbs, buttocks, back) is painful, swollen or tender to touch.
  • The patient may be unconscious, confused, dehydrated or febrile.
  • Paresis or sensory disturbance may be present in the limbs (increased compartment pressure).
  • Urine may be dark (myoglobin), orurine output may be decreased.
  • Urine strip test may be positive to haematuria (due to myoglobin), even when no red cells are seen in the sediment.

Diagnosis

  • If rhabdomyolysis is suspected, measure serum creatine kinase (CK).
    • CK activity is often clearly elevated (10 000-100 000 U/l).
    • In clinical practice, the measurement of other muscle enzymes is not needed.
    • Plasma myoglobin concentration is also increased.
  • Other typical laboratory findings include
    • hypocalcaemia (calcium deposited in muscle tissue)
    • hyperkalaemia
    • hyperphosphataemia (renal failure and release from cells)
    • urine dipstick test positive (+) for erythrocytes in approximately 50% of patients
    • increased serum creatinine as renal failure develops.
  • Differential diagnosis: Local symptoms may resemble those of deep venous thrombosis.
  • Palpate the muscles, note tenderness and swelling.

Treatment

  • The patient is usually admitted to hospital.
  • In primary care the first aid consists of the correction of hypovolaemia and dehydration.
    • Start with physiological saline.
      • 1 000 ml during the first hour
      • Followed by 400 ml/h
    • The aim is to prevent the development of acute renal failure Acute Kidney Injury, caused by myoglobin which is being released from the muscles.
  • Follow-up treatment in a hospital
    • Intensive fluid therapy is the cornerstone of the treatment. The target is to maintain diuresis of 200-300 ml/h.
      • Initially 1 000 ml of 0.9% NaCl over 1 hour
      • Fluid therapy may also be continued with a solution containing 0.3% NaCl and 5% glucose, at rate 400 ml/h.
      • Alkalization of the urine may be considered if the urine pH is less than 6.5 (even if there is no evidence to support this therapy): administer by turns 1 000 ml of plain 0.9% NaCl and 1 000 ml of 0.45% NaCl with an addition of 50-75 ml of 7.5% bicarbonate.
    • Dialysis is indicated if the patient is anuric and diuresis is not induced with rehydration.
      • Dialysis will have no effect on the renal state, but will keep the patient alive until renal function spontaneously returns. This may take several days, even weeks.
    • Fasciotomy is indicated if increased compartment pressure threatens to cause muscle necrosis or nerve damage Muscle Compartment Syndromes; readily consult a surgeon.
    • Correction of symptomatic hypocalcaemia must be carried out cautiously, because hypercalcaemia often develops during recovery. Asymptomatic hypocalcaemia requires no treatment.

Prognosis

  • Prognosis is good even in cases where renal failure has developed, since the failure is reversible.
    • If compartment syndrome is not treated early enough, residual nerve and muscle damage may persist.

References

  • Bosch X, Poch E, Grau JM. Rhabdomyolysis and acute kidney injury. N Engl J Med 2009;361(1):62-72. [PubMed]