<prompt> Causes of thrombocytopenia are all EXCEPT341-H 468-CMDT-09DICB12 folate deficiencySLERheumatoid arthritis  <response>: Rheumatoid arthritis 341-H 468-CMDT 719-H17thCauses of Thrombocytopenia Decreased marrow production of megakaryocytes- Marrow infiltration with tumour, fibrosis.- Marrow failures - aplastic, hypoplastic anemias, drug effects Splenic sequestration of circulating platelets- Splenic enlargement due to tumour infiltration- Splenic congestion due to portal hypertension Hypersplenism Increasing destruction of circulating plateletsII Non immune destruction - Vascular prosthesis, cardiac valves, DIC, sepsis, TTP, Hemolytic-uremic syndrome, Hemangiomas, AIDS, liver failure, vasculitisIII Immune destruction- Auto antibodies to platelet antigens- ITP.- Drug induced antibodies Sulfonamides, quinine, thiazides, Cimetidine, gold and heparin MC- Secondary SLE, CLL, post transfusion purpura viral antigens and bacterial sepsis.Bone marrow disorders - Aplastic anemia, Hematologic malignancies, Myelodysplasia, Megaloblastic anemia, chronic alcoholism 501-CMDT-05 Rheumatoid arthritis and ulcerative colitis causes significant elevation of the platelet count as may chronic infection. The thrombocytosis of iron deficiency is observed only when anaemia is significant. The platelet count is temporarily elevated after splenectomy 484-CMDT-05. 