An international consensus committee described features for the antiphospholipid syndrome and related conditions. One of the related conditions is persistent thrombocytopenia.


NOTE: A patient who meets the clinical criteria (vascular thromboses and/or pregnancy morbidity) for the antiphospholipid syndrome is excluded from the definition.



(1) laboratory features of the antiphospholipid syndrome, with the presence of:

(1a) lupus anticoagulant

(1b) anticardiolipin antibody

(1c) anti-beta-glycoprotein I antibody

(1d) mixture of 2 or more types

(2) presence of thrombocytopenia (platelet count < 100,000 per µL) on at least 2 measurements at least 12 weeks apart

(3) exclusion another explanation for thrombocytopenia including:

(3a) disseminated intravascular coagulopathy (DIC)

(3b) thrombotic thrombocytopenic purpura (TTP)

(3c) hemolytic uremic syndrome (HUS)

(3d) heparin-induced thrombocytopenia

(3e) pseudothrombocytopenia


Additional descriptors:

(1) presence or absence of SLE

(2) severity


Platelet Count per µL


50,000 - 99,999


< 50,000




• Mild thrombocytopenia (levels >= 100,000 per µL) is not included in the definition.

• Severity descriptions is meaningful if the platelet counts are relatively stable.


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