Myalgia

Differential Diagnosis

• Infection:
  • Viral infection (e.g. Influenza virus)
  • Bacterial infection
  • Spirochete infection (E.g. Dengue fever; Trichinella infection)
• Drugs:
  • Statins
  • Bisphosphonates
  • corticosteroids
  • ciprofloxacin
  • clofibrate
  • colchicine
  • chloroquine
  • emetine
  • aminocaproic acid
  • zidovudine
  • bretylium
  • penicillamine
  • drugs causing hypokalemia
• Metabolic disorders:
  • Vitamin D deficiency;
  • Mitochondrial myopathy;
  • Scurvy;
  • Osteomalacia
• Fibromyalgia
• Endocrine:
  • hypothyroidism;
  • hyperthyroidism;
  • Cushing’s syndrome;
  • Adrenal insufficiency;
  • Hyperparathyroidism
• Polymyalgia rheumatica
• Rhabdomyolysis (and anything that can cause rhabdomyolysis)
• Myositis (muscle inflammation): e.g, polymyositis, dermatomyositis
• Systemic lupus erythematosus (SLE)
• Rheumatoid arthritis
• Inclusion body myositis
• Sarcoidosis
• Scleroderma
• Sjögren’s syndrome
• Psychiatric (e.g. somatic manifestations of depression)
• Domestic abuse; Crush injury
• Lyme disease
• Ehlers Danlos (Hypermobility syndrome)
• HIV myopathy
• Hypophosphatemia
• Hypokalemia
• Hypothermia
• Prolonged immobility, eg, after a drug overdose.
• Strenuous exercise (overuse) or heat stroke
• Seizure
• Severe volume contraction
• Alcoholism
• Muscular dystrophy, eg, Duchenne, Becker, limb-girdle, facioscapulohumeral (FSH); Myotonic dystrophy; Myotonia congenita
• Compartment syndrome; Muscle infarction
• Neuropathic
• Chronic fatigue syndrome
• Vasculitis
• Sarcocystosis
• Spinal stenosis
• Diabetic lumbosacral plexopathy

Evaluation

• Myalgias can be divided into diffuse (systemic) myalgias vs. Localized myalgias.
• Muscle pain can come from Rhabdomyolysis, Myositis, or Myopathy.