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🌱 來自: approach to rheumatic disease

inflammatory marker & autoantibody testing

Inflammatory markers (Mod Rheumatol 2009;19:469; NEJM 1999;340:448)

• ESR:
  • indirect measure of inflammation [↑ RBC aggregation due to acute-phase proteins (fibrinogen, Ig)];
  • slow to rise;
  • may ↑ w/ age, preg., anemia, obesity, ESRD. Ddx for >100: malig. esp. MM, lymphoma;
  • GCA or other vasculitis;
  • endocarditis, TB, osteomyelitis.
• CRP: direct measure of inflammation (protein produced by liver, part of innate immune system); typically rises and falls before the ESR w/ treatment/resolution of process

Autoantibody testing (Best Pract Res Clin Rheumatol 2014;28:907)

• ANA (anti-nuclear Ab): screening
  • test for Ab directed against nuclear proteins.
• Order ANA only when clinical suspicion for CTD b/c nonspecific:
  • 1:40 (very low ⊕, 25-30% of healthy Pts);
  • 1:80 (low ⊕, 10-15% of healthy Pts);
  • ≥1:160 (⊕, 5% of healthy Pts). May be ⊕ in Pts prior to clin manifest (NEJM 2003;349:1526;
  • Arthritis Res Ther 2011;13:1).
• If ANA ⊕ and high clinical suspicion for CTD, consider testing for Ab against dsDNA, Smith, Ro/La, RNP, Scl-70 and myositis-specific Abs (highly specific for various CTD)
• ANA does not correlate well w/ disease activity, ∴ no clinical value in serial testing
• ANA also ⊕ in:
  • AIH,
  • PBC,
  • thyroid disease,
  • certain infxns and malignancies,
  • IBD,
  • IPF
• RF and anti-CCP (see “Rheumatoid Arthritis”)