From the Guidelines
For this 34-year-old African American male with elevated CK levels, I recommend further evaluation with a comprehensive neuromuscular assessment, including a detailed medication history, complete myositis panel, genetic testing, electromyography (EMG), and nerve conduction studies, as suggested by the most recent guidelines 1. First, obtain a detailed medication history focusing on potential myotoxic effects of his current medications, particularly Adderall and Truvada. Order a complete myositis panel including anti-Jo-1, anti-SRP, and anti-HMGCR antibodies. Consider genetic testing for inherited myopathies, particularly those more common in African American populations such as sarcoglycanopathies. Perform electromyography (EMG) and nerve conduction studies to differentiate between myopathic and neurogenic processes. If these tests are inconclusive, a muscle biopsy may be necessary. The declining CK levels (2000 to 557) suggest improvement, but the persistent elevation warrants investigation. The normal kidney function is reassuring, but monitor it closely as rhabdomyolysis can cause renal injury. The recently treated vitamin D deficiency could contribute to muscle symptoms, so recheck vitamin D levels to ensure normalization, following the guidelines for vitamin D supplementation 1. Drug-induced myopathy is a strong possibility given his medication regimen - Truvada has been associated with myopathy in some patients, and stimulants like Adderall can cause muscle symptoms. The normal TSH and negative ANA help rule out thyroid myopathy and certain autoimmune conditions, but the elevated ESR indicates ongoing inflammation that requires further investigation, as outlined in the management of immune-related adverse events in patients treated with immune checkpoint inhibitor therapy 1. Given the potential for myositis, it is essential to follow the guidelines for the management of myositis, including the use of corticosteroids and other immunosuppressive therapies if necessary, as recommended in the most recent guidelines 1.
From the Research
Evaluation of Elevated CK Levels
- The patient's CK levels were found to be 2000 in the setting of a URI with "muscle spasms," which decreased to 557 after 10 days 2.
- The patient's ESR was 32, and ANA was negative, with normal TSH and CBC results 2.
- The patient has stable mild alkaline phosphate and ALT elevations, with normal kidney function and urinalysis 2.
Medications and Vitamin D Deficiency
- The patient is taking Adderall, mirtazapine, Truvada, and Valacyclovir 2.
- The patient was recently treated for severe vitamin D deficiency, which may be relevant to muscle weakness and elevated CK levels 2.
Diagnostic Considerations
- Muscle biopsy may be considered to evaluate the patient's elevated CK levels and muscle spasms, especially if electromyography (EMG) findings suggest myopathy 3, 4.
- EMG findings, such as short-duration motor unit potentials and fibrillation potentials, can help confirm myopathy and indicate specific pathologic changes on muscle biopsy 4.
- Muscle biopsy can help distinguish between myositis and dystrophy, which can present with similar clinical features 5, 6.
Further Evaluation
- Consider ordering EMG to evaluate for myopathic changes and guide further diagnostic testing 4.
- If EMG findings suggest myopathy, consider muscle biopsy to evaluate for inflammatory or necrotizing myopathy 3, 5.
- Review the patient's medication list and consider potential drug-related myopathy, especially with statin use 5.