From the Research
Management of myoglobinuria with low CPK levels should focus on preventing acute kidney injury through aggressive intravenous fluid administration, with the most recent and highest quality study suggesting that serum myoglobin is a more sensitive and specific test than serum CPK for predicting acute kidney injury 1. The goal is to maintain urine output above 200-300 mL/hour, and urine alkalinization with sodium bicarbonate may be considered to reduce myoglobin precipitation in renal tubules. Key considerations in management include:
- Aggressive intravenous fluid administration with normal saline at 200-500 mL/hour initially
- Monitoring and correcting electrolyte abnormalities, particularly hyperkalemia, hypocalcemia, and hyperphosphatemia
- Identifying and treating the underlying cause of myoglobinuria, whether it's exertional, medication-induced, or related to other conditions like metabolic myopathies
- Considering the use of diuretics like mannitol or furosemide if fluid overload occurs, but only after adequate hydration
- Recognizing that myoglobin is cleared more rapidly than CPK, which may explain the discrepancy between myoglobinuria and low CPK levels 2. It's also important to note that the use of sodium bicarbonate and mannitol in the management of rhabdomyolysis is not entirely justified, and aggressive early volume resuscitation with normal saline should continue to be the principal focus of therapy 3. Overall, the management of myoglobinuria with low CPK levels requires a comprehensive approach that prioritizes the prevention of acute kidney injury and addresses the underlying cause of the condition.