From the Guidelines
Incidental creatine kinase (CK) elevation of 2000 U/L is most likely caused by strenuous exercise, muscle trauma, or medications, and should be worked up with a thorough history and physical examination, followed by laboratory testing to confirm elevation and rule out underlying conditions. The workup should begin with a thorough history and physical examination focusing on medication use, exercise patterns, muscle symptoms, and family history of muscle disorders. Laboratory testing should include repeat CK measurement to confirm elevation, comprehensive metabolic panel, thyroid function tests, and urinalysis to check for myoglobinuria, as suggested by general medical knowledge and not specifically addressed in 1, 1, or 1. If the patient is on a statin, it should be temporarily discontinued to see if CK levels normalize. For persistent unexplained elevations, additional testing may include inflammatory markers (ESR, CRP), autoimmune panels if inflammatory myopathy is suspected, and aldolase levels. Electromyography and muscle biopsy may be considered for persistent elevations without clear cause, as these are standard diagnostic procedures for muscle disorders. Genetic testing for hereditary myopathies should be considered if there is a family history, as this can help identify underlying genetic conditions that may be contributing to the CK elevation. Most incidental CK elevations without symptoms are benign and may resolve with observation, but monitoring is important to detect potential muscle damage early, especially if the patient is continuing medications that may cause myopathy. It's also important to note that patients with chronic kidney disease (CKD) or end-stage renal disease (ESRD) may have elevated CK levels due to decreased glomerular filtration, as mentioned in 1, but this is not directly relevant to the workup of incidental CK elevation. Overall, the goal of the workup is to identify any underlying conditions that may be contributing to the CK elevation and to monitor for potential muscle damage, in order to prioritize morbidity, mortality, and quality of life as the outcome.
From the FDA Drug Label
Atorvastatin calcium may cause myopathy (muscle pain, tenderness, or weakness associated with elevated creatine kinase [CK]) and rhabdomyolysis. Risk Factors for Myopathy Risk factors for myopathy include age 65 years or greater, uncontrolled hypothyroidism, renal impairment, concomitant use with certain other drugs (including other lipid-lowering therapies), and higher atorvastatin calcium dosage
Incidental CK elevation of 2000 can be caused by:
- Myopathy associated with statin use, including atorvastatin calcium
- Rhabdomyolysis, a serious condition that can occur as a result of myopathy
- Immune-Mediated Necrotizing Myopathy (IMNM), a rare autoimmune myopathy associated with statin use
Workup should include:
- Discontinuation of atorvastatin calcium if markedly elevated CK levels occur or myopathy is diagnosed or suspected
- Temporary discontinuation of atorvastatin calcium in patients experiencing an acute or serious condition at high risk of developing renal failure secondary to rhabdomyolysis
- Informing patients of the risk of myopathy and rhabdomyolysis when starting or increasing atorvastatin calcium dosage
- Instructing patients to promptly report unexplained muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever 2 2 2
From the Research
Causes of Incidental CK Elevation
- Acute myocardial infarction 3
- Drug intake 3
- Fall 3
- Haematoma 3
- Intramuscular injection 3
- Malignancy 3
- Exertional muscle damage 4
- Statin use 5
- Concentric needle EMG examination 6
Workup for Incidental CK Elevation of 2000
- Assess patient history for acquired and hereditary etiologies 7
- Perform nerve conduction study and EMG 7
- Consider further testing if CK level is high and patient is young 7
- Look for presence of weakness, as it increases the likelihood of a specific cause other than idiopathic or familial hyperCKemia 7
- Be aware that many etiologies do not have treatments that alter clinical outcomes, and good communication with patients and primary care providers is essential for longitudinal surveillance 7
- Note that exertional muscle damage can cause profound CK elevations without renal impairment 4
- Avoid CK measurements 4 to 48 hours following concentric needle EMG examination due to potential for false positive results 6