antiphospholipid syndrome


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  • Sydney criteria

    • 1 clinical criteria
      • thrombosis
      • pregnancy issues
        • abortion of nml fetus >= 10 wks
        • premature < 34 wk from (pre)eclampsia or placenta insufficiency
        • 3+ consecutive abortions < 10 wk
    • 1 lab criteria, twice detected at least 12 wks apart
      • lupus anticoagulant (LA)
        • elevated dRVVT ratio, delta HPL
        • mixing nml plasma fails to correct (evidence of inhibitor)
        • adding phospholipid corrects
      • anticardiolipin (aCL)
        • ELISA
        • IgG > 40 GPL
        • IgM > 40 MPL
        • or 99th %
      • anti-beta-2 glycoprotein-I (anti-beta2-GPI)
        • ELISA
        • IgG > 40 GPL
        • IgM > 40 MPL
        • or 99th %

  • Testing

    • consider testing if: thrombosis, pregnancy issues
    • initial testing shortly after clinical event
    • confirmatory testing > 12 weeks later
    • lupus anticoagulant = dRVVT ratio, delta HPL
      • screening: aPTT, HPL, dRVVT
        • lupus sensitive aPTT = less phospholipids
        • HPL = dilute version of aPTT
        • dRVVT = snake venom activates factor X
      • confirmatory: dRVVT ratio, delta HPL, plt neutralization
        • dRVVT ratio = dRVVT screen / dRVVT with PL
        • delta HPL = HPL screen - HPL with PL
        • plt neutralization = PL on plt soaks up lupus inhibitor
      • mixing studies = PL corrects, normal plasma don't = inhibitor
      • false negative: acute thrombosis, hydroxychloroquine, pregnancy
      • false positive: anticoagulation, some uses replitase (resistant) to r/o anticoag
    • antiphospholipid (aPL) = anticardiolipin, anti-beta2glycoprotein I
      • transient aPL in healthy pts
      • infection can cause IgM aCL
      • certain drugs can cause transient IgM
      • SLE can have aPL +/- APS
      • autoimmune disease and malignancy can cause aPL
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