From the Guidelines
In patients with rhabdomyolysis, CK levels should be trended downwards but do not necessarily need to return to normal, as the primary focus is on preventing and managing complications such as acute kidney injury and electrolyte imbalances, rather than achieving complete normalization of CK levels. This approach is supported by the understanding that CK levels can remain elevated for an extended period after the acute phase has resolved 127. The goal is to ensure that CK levels decrease significantly, typically to below 5,000 U/L, and that the patient shows clinical improvement with normalized renal function and electrolytes 1. Aggressive IV fluid administration, usually with isotonic saline at 200-300 mL/hour initially, should be continued until CK levels decrease and the patient's condition improves. It's also important to monitor for hyperkalaemia and assess kidney function through plasma creatinine tests, as myoglobin can cause intraluminal kidney tubular obstruction, leading to reduced glomerular filtration rate 1.
Key considerations in managing rhabdomyolysis include:
- Monitoring CK levels to ensure a downward trend
- Aggressive fluid resuscitation to prevent acute kidney injury
- Managing electrolyte abnormalities, particularly hyperkalaemia
- Assessing kidney function regularly
- Being aware that CK levels can peak within 24-72 hours of muscle injury and may remain elevated for 7-10 days after the acute phase has resolved.
The measurement of plasma myoglobin may offer earlier insight into the risk of acute kidney injury than CK levels, as it has an earlier peak plasma concentration and may be more sensitive and specific in identifying this risk 1. However, the primary clinical decision should be based on the trend of CK levels and overall clinical improvement, rather than waiting for these levels to completely normalize.
From the Research
Rhabdomyolysis Treatment
- The primary goal of treatment in rhabdomyolysis is to prevent acute kidney injury (AKI) and address potential complications such as hyperkalemia and compartment syndrome 2, 3, 4.
- Early and aggressive fluid resuscitation is widely recommended to restore renal perfusion and increase urine flow, with some studies suggesting the use of ≥12 l daily intravenous infusion of alkaline solution 5.
- However, the use of bicarbonate-containing fluids is not universally supported, with one study finding that bicarbonate therapy was associated with a higher incidence of AKI, dialysis dependency, and mortality compared to non-bicarbonate therapy 6.
Creatine Kinase (CK) Levels
- Elevated CK levels are a key diagnostic criterion for rhabdomyolysis, with some studies suggesting that a level of at least 10 times the upper limit of normal is indicative of the condition 3.
- The trend of CK levels is also important, with a rapid decrease in CK levels to near-normal values considered a reasonable definition of rhabdomyolysis 3.
- However, there is limited evidence to suggest that trending CK levels to normal is a specific treatment goal in rhabdomyolysis, with treatment instead focused on addressing the underlying causes and preventing complications 2, 3, 4, 5, 6.
Complications and Outcomes
- Rhabdomyolysis can have serious complications, including AKI, hyperkalemia, and compartment syndrome, which require prompt treatment 2, 3, 4.
- The mortality rate for rhabdomyolysis is approximately 10%, with higher rates seen in patients with AKI 3.
- Early recognition and treatment of rhabdomyolysis are critical to improving outcomes, with delayed treatment associated with increased morbidity and mortality 2, 3, 4, 5, 6.