Criteria for the diagnosis of ITP in the adult - all of the following:
(1) thrombocytopenia, with platelet count <= 50,000 per µL
(2) increased megakaryocytic mass seen on bone marrow biopsy
(3) absence of the following:
(3a) splenomegaly
(3b) disseminated intravascular coagulopathy (DIC)
(3c) thrombotic thrombocytopenic purpura (TTP) or hemolytic-uremic syndrome (HUS)
(3d) post-transfusion purpura
(3e) hematologic or lymphoreticular malignancy
(3f) systemic lupus erythematosus (SLE)
(3g) hemolytic anemia with or without accompanying leukopenia
(3h) infection-related thrombocytopenia (infectious mononucleosis, CMV, etc.)
(3i) drug-induced thrombocytopenia (immune or direct toxicity)
(4) presence of anti-platelet antibodies
where:
• The presence of splenomegaly suggests a secondary form of thrombocytopenia.
• The diagnosis may be made in the absence of anti-platelet antibodies is the testing is unavailable or delayed.
• ITP may follow a viral infection due to a post-infectious immune response rather than a direct effect of the virus.
