Medical Care
All patients with suspected myoglobinuria or rhabdomyolysis should be admitted for intravenous (IV) hydration and management of complications. A creatine kinase (CK) level of more than 5000 U/L is considered to be an absolute indication for hospitalization and vigorous IV hydration. Initial treatment focuses on preventing myoglobin precipitation in the urine by inducing and maintaining a brisk diuresis. Immediately administer saline to patients with suspected myoglobinuria or rhabdomyolysis because early hydration is the key to ameliorate acute kidney injury. Isotonic saline boluses of 20 mL/kg should be initially administered, with repeat boluses depending on the hydration status of the patient. This should be followed by continued hydration with IV fluids given at a rate of 2-3 times maintenance. [4, 20]
Achievement of a urine output goal of 2-3 mL/kg/h is recommended. IV hydration should be continued until the CK level is consistently less than 1000 U/L, the urine clears, and the patient is able to maintain adequate oral hydration.
Follow-up with mannitol to induce diuresis, supported by adequate IV fluids, has been advocated. Mannitol causes diuresis, which minimizes intratubular myoglobin deposition, acts as a free radical scavenger and reduces tubule cell damage, and may act as a direct renal vasodilator. However, the clinical benefit of this therapy remains unproven. In retrospective studies, volume expansion with saline alone prevented acute renal failure, and mannitol had no additional benefit. [21]
Raising the pH of the urine to 6.5 or more can be facilitated by adding sodium bicarbonate to the fluids. Alkalinization of the urine has been postulated to minimize the breakdown of myoglobin into its nephrotoxic metabolites and to reduce crystallization of uric acid, thereby decreasing damage to tubule cells. However, this modality of therapy remains somewhat controversial because large volumes of crystalloid alone may be sufficient to alkalinize the urine and because bicarbonate therapy can aggravate the hypocalcemia. No large randomized trials have demonstrated that alkalinization of urine is superior to early aggressive hydration with crystalloid in the management of rhabdomyolysis.
Hyperkalemia and hypocalcemia may require emergent treatment.
Patients with crush injuries and trauma require treatment for the soft tissue and bony injuries.
Patients with compartment compression due to muscle edema may require fasciotomy.
CK levels generally peak on day 3 and then rapidly decrease by half every 24-48 hours.
Further inpatient care
Hemodialysis or continuous veno-veno hemodialysis (CVVHD) may be needed to treat acute renal insufficiency in patients with myoglobinuria. Recovery often occurs in 10-14 days.
Electrolyte complications of rhabdomyolysis, including hyperkalemia and hypocalcemia, may need immediate treatment.
In the recovery phase, patients may develop hypercalcemia as calcium precipitated in damaged tissue returns to the circulation.
Long-term diuresis may cause hypokalemia.
Surgical Care
Surgical debridement may be needed if muscle damage or necrosis is extensive. Fasciotomy may be required to manage compartment compression syndrome.
Consultations
Nephrologists may facilitate the safe initiation of diuresis to avoid dialysis. If dialysis is needed, consultation with a nephrologist is necessary.
Activity
Activity is restricted by the extent of muscle damage. Persons who have had exertional myoglobinuria must limit their future activity and maintain adequate hydration.
Prevention
Patients with metabolic muscle diseases must avoid trauma, overexertion, dehydration, and heat injuries.
Long-Term Monitoring
Patients may need extensive rehabilitation for muscle damage.
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Model of helical domains in myoglobin.
