From the Guidelines
Blood tests for myositis should include creatine kinase (CK), transaminases (AST, ALT), lactate dehydrogenase (LDH), aldolase, troponin, and inflammatory markers (ESR and CRP) to evaluate muscle inflammation and myocardial involvement, as recommended by the American Society of Clinical Oncology clinical practice guideline 1. When evaluating a patient for myositis, it is essential to consider the diagnostic work-up, which includes a complete rheumatologic and neurologic history, examination of muscle strength, and skin examination for findings suggestive of dermatomyositis.
Key Blood Tests
- CK, transaminases (AST, ALT), LDH, and aldolase to assess muscle damage
- Troponin to evaluate myocardial involvement
- Inflammatory markers (ESR and CRP) to measure inflammation levels
Additional Tests
Consider electromyography (EMG), imaging (MRI), and/or biopsy on an individual basis when diagnosis is uncertain, and overlap with neurologic syndromes, such as myasthenia gravis, is suspected 1. Paraneoplastic autoantibody testing for myositis and neurologic conditions, such as myasthenia gravis, may also be considered. Regular monitoring of these markers, including CK, ESR, and CRP, helps assess treatment effectiveness and disease progression, as recommended by the American Society of Clinical Oncology clinical practice guideline 1.
From the Research
Blood Tests for Myositis
- Blood tests are used to diagnose and monitor myositis, with various markers and enzymes measured to assess muscle damage and disease activity 2, 3, 4, 5, 6
- Commonly used blood tests for myositis include:
- Creatine kinase (CK) levels, which are often elevated in myositis patients 2, 4, 6
- Aldolase levels, which can be elevated in some myositis patients, particularly those with damaged early regenerating muscle cells 3, 5
- Aspartate aminotransferase (AST) levels, which can be elevated in myositis patients 2, 6
- Lactate dehydrogenase (LDH) levels, which can be elevated in myositis patients 6
- Myoglobin levels, which can be elevated in myositis patients 6
- The use of these blood tests can help diagnose and categorize patients with myopathy, and can be used in conjunction with other diagnostic tools, such as muscle biopsy 2, 4, 5
- Some studies have found that isolated elevation of aldolase can be a potential biomarker of damaged early regenerating muscle cells in myositis patients 3, 5
- Laboratory test abnormalities are common in polymyositis and dermatomyositis, and can differ among clinical and demographic groups 6