From the Guidelines
The initial workup for a patient presenting with myalgia should include a complete rheumatologic and neurologic history, physical examination, and laboratory tests such as CK, transaminases, lactate dehydrogenase, and inflammatory markers to evaluate muscle inflammation and potential myocardial involvement 1. The workup should prioritize identifying potential causes of myalgia, including autoimmune conditions, medication side effects, and recent infections.
- Key elements of the history and physical examination include:
- Documenting the pattern, duration, and severity of muscle pain
- Associated symptoms, such as fever, rash, or joint pain
- Medication use, particularly statins or immunotherapy
- Recent infections or physical activity
- Laboratory tests should include:
- Complete blood count (CBC)
- Comprehensive metabolic panel
- Creatine kinase (CK)
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Thyroid function tests
- Troponin to evaluate myocardial involvement
- Additional tests may be warranted based on clinical suspicion, such as:
- Antinuclear antibodies (ANA) for autoimmune conditions
- Vitamin D levels
- HMG-CoA reductase antibodies for immune-mediated necrotizing myopathy
- Electromyography (EMG) to distinguish between myopathic and neurogenic processes
- Imaging, such as MRI, for focal symptoms or suspected inflammatory myopathies
- Muscle biopsy in cases of persistent unexplained myalgia According to the most recent study 1, myositis may be a severe condition, and prompt recognition and early management are imperative, with discontinuation or interruption of checkpoint inhibitors and high-dose systemic glucocorticoids as first-line treatment.
- The study also highlights the importance of cardiac evaluation, including cardiac troponin and electrocardiography, in patients with myositis or suspected myositis, due to the increased risk of myocarditis.
- The task force agreed that further evaluation is warranted, particularly on the impact on tumor response, but considering the high mortality rate of myositis complicated with myocarditis or severe respiratory failure, rescue therapy with T-cell directed therapies, such as abatacept or alemtuzumab, may be considered in refractory situations 1.
From the Research
Initial Workup for Myalgia
The initial workup for a patient presenting with myalgia (muscle pain) involves a comprehensive approach to determine the underlying cause.
- A detailed medical history is essential to identify any underlying conditions that may be contributing to the myalgia 2.
- A full neurologic assessment is also necessary to evaluate for any neuromuscular disorders that may be causing the myalgia 2.
- Laboratory tests, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), can help identify inflammatory conditions like polymyalgia rheumatica (PMR) 3, 4, 5, 6.
- Electromyography (EMG) and nerve conduction studies may be required to evaluate for any muscle or nerve damage 2.
- Muscle imaging, genetic testing, and muscle biopsy may also be necessary to make a diagnosis in some cases 2.
Diagnostic Considerations
When evaluating a patient with myalgia, it is essential to consider various diagnostic possibilities, including:
- Metabolic muscle diseases
- Inflammatory muscle diseases
- Dystrophic myopathies
- Myotonic muscle disorders
- Polymyalgia rheumatica (PMR)
- Fibromyalgia
- Other conditions that may cause myalgia, such as hypothyroidism or obesity 2, 5.
Laboratory Tests
Laboratory tests play a crucial role in the diagnosis of myalgia.
- ESR and CRP are commonly used to evaluate for inflammatory conditions like PMR 3, 4, 5, 6.
- Serum amyloid A (SAA) may be a useful therapeutic marker in some cases of PMR 6.
- Other laboratory tests, such as complete blood count, blood chemistry, and thyroid function tests, may also be necessary to evaluate for underlying conditions that may be contributing to the myalgia.