Polymyositis Evaluation

Aka: Polymyositis Evaluation, Dermatomyositis Evaluation

1. See Also
   1. Polymyositis
   2. Dermatomyositis
2. Labs: Muscle Enzymes
   1. Serum Aldolase
   2. Alanine Aminotransferase (ALT)
   3. Aspartate Aminotransferase (AST)
   4. Lactate Dehydrogenase (LDH)
   5. Creatine Phosphokinase (CPK)
   6. Carbonic Anhydrase (isoenzyme III)
      1. Limited availability
3. Lab: Rheumatologic
   1. Erythrocyte Sedimentation Rate (ESR)
      1. Increased in 50% of cases
      2. Poor correlation with disease activity
   2. Rheumatoid Factor
      1. Increased in 20% of cases
      2. Associated with overlap syndrome
   3. Antinuclear Antibody (ANA)
      1. Seen in 60-80% Dermatomyositis and Polymyositis
   4. Juvenile Dermatomyositis associated labs
      1. Neopterin
      2. Factor VIII-related Antigen (Von Willebrand Factor)
4. Labs: Specific Autoantibodies
   1. Anti-Jo1
      1. Seen in 20% of Dermatomyositis
   2. Anti-EJ
      1. Associated with Dermatomyositis
   3. Signal Recognition Particle (SRP)
      1. Seen in 5% of Polymyositis
      2. Associated in severe, acute-onset Polymyositis
         1. Treatment resistant Dermatomyositis, Polymyositis
         2. Associated with cardiac involvement
   4. Anti-Mi2
      1. Seen in 15-20% of classic Dermatomyositis
      2. Associated conditions
         1. Treatment-responsive form
         2. Shawl sign in Dermatomyositis
         3. Prominent cuticular changes
   5. Anti-PM-Scl
      1. Seen in overlap syndrome
      2. Associated conditions
         1. Dermatomyositis and Polymyositis
         2. Scleroderma
   6. Anti-Ku
      1. Seen in overlap syndrome
      2. Associated conditions
         1. Dermatomyositis and Polymyositis
         2. Scleroderma
         3. Systemic Lupus Erythematosus
5. Diagnostics: Electromyogram (EMG)
   1. False negative in 10% of cases
   2. Myopathic or myogenic pattern
      1. Short duration, polyphasic motor unit potentials
      2. Spontaneous fibrillation potentials
6. Monitoring: Ovarian Cancer Screening in Women
   1. Initial gynecologic exam and every 6-12 months x2 years
   2. Baseline CA-125 level
   3. Baseline Mammogram
   4. Baseline Transvaginal Ultrasound of the ovaries
7. References
   1. Ioannou (1999) Curr Opin Rheumatol 11(6):468-74 [PubMed]
   2. Koler (2001) Am Fam Physician 64(9):1565-72 [PubMed]
   3. Pachman (1995) Pediatr Clin North Am 42:1071-98 [PubMed]
   4. Sigurgeirsson (1992) N Engl J Med 326:363-7 [PubMed]
   5. Whitmore (1994) Medicine 73:153-60 [PubMed]