Can lupus cause myalgia (muscle pain)?

Myalgia in Systemic Lupus Erythematosus

Yes, lupus commonly causes myalgia (muscle pain), with studies showing that myalgia occurs in approximately 55-68% of patients with systemic lupus erythematosus (SLE). 1

Musculoskeletal Manifestations in Lupus

Musculoskeletal symptoms are among the most prevalent manifestations in SLE, affecting over 90% of patients throughout their disease course 2. These manifestations typically include:

• Myalgia (muscle pain): Present in 55.65% of patients at initial presentation 1
• Arthralgia (joint pain): Present in 68.75% of patients 1
• Arthritis: Present in 48.31% of patients 1
• True myositis: Less common, occurring in only about 2.47% of patients 1

Mechanism of Muscle Pain in Lupus

The nature of muscle pain in lupus can have several causes:

1. Direct muscle inflammation: Although less common than simple myalgia, true inflammatory myositis can occur in lupus patients 3

2. Referred pain: Much of the myalgia in lupus patients may be due to pain referred from adjacent inflamed joints 3

3. Fibromyalgia overlap: Chronic widespread pain typical of fibromyalgia is frequently associated with SLE and can complicate assessment of disease activity 4

4. Medication side effects: Some treatments for lupus, particularly corticosteroids, can contribute to muscle symptoms 3

Diagnostic Approach

When evaluating myalgia in a patient with suspected or confirmed lupus:

• Laboratory testing:

  • Inflammatory markers (ESR, CRP) are typically elevated in active lupus 5
  • Creatine kinase (CK) levels should be checked to distinguish between simple myalgia and true myositis 5
  • CK levels are usually normal in patients with myalgia alone but elevated in true myositis 6
  • Autoantibody testing (ANA, anti-dsDNA, anti-Sm) helps confirm SLE diagnosis 7

• Imaging:

  • MRI can show increased intensity and edema in affected muscles if true myositis is present 5
  • Musculoskeletal ultrasound is an accessible and affordable method to assess joint and muscle involvement 2

• Electromyography (EMG):

  • May show muscle fibrillations if myopathy is present 5
  • Typically normal in simple myalgia without myositis 6

• Muscle biopsy:

  • Reserved for cases where true inflammatory myositis is suspected 5
  • Can help distinguish between lupus myositis and other causes of muscle inflammation 3

Management of Myalgia in Lupus

Treatment should be tailored based on severity and underlying cause:

1. For mild to moderate myalgia without evidence of myositis:

   • NSAIDs for symptom relief 6
   • Hydroxychloroquine as part of standard SLE management 7

2. For myalgia associated with active lupus:

   • Treatment of underlying disease activity with appropriate immunosuppression 7
   • Low-dose corticosteroids may be beneficial 7

3. For true inflammatory myositis:

   • Higher-dose corticosteroids (prednisone 0.5-1 mg/kg/day) 5
   • Addition of immunosuppressive agents (methotrexate, azathioprine, or mycophenolate mofetil) 5
   • IVIG for refractory cases 5

Important Considerations

• Distinguish from fibromyalgia: Secondary fibromyalgia is common in SLE patients and may not correlate with disease activity but can significantly impact quality of life 4

• Watch for life-threatening complications: If myositis is present, cardiac evaluation is essential as myocarditis can be a potentially fatal complication 6, 5

• Monitor for medication side effects: Steroid myopathy can mimic or exacerbate muscle symptoms 3

• Regular assessment: Ongoing evaluation of muscle strength and enzymes is recommended to monitor disease activity and treatment response 5

By understanding the various causes of myalgia in lupus patients and implementing appropriate diagnostic and treatment strategies, clinicians can effectively manage this common symptom and improve patients' quality of life.