34 Fig 34.1 Blood film showing clumping of platelets. Table 34.1 ITP, immune thrombocytopenia; DIC, disseminated intravascular coagulation. In general terms there are four possible processes leading to thrombocytopenia:
Thrombocytopenia
This phenomenon causes an artefactual thrombocytopenia in the automated blood count.
Causes
Pathogenesis
Disease examples
Failure of production
Leukaemia, myelodysplasia, aplastic anaemia, megaloblastic anaemia, myelofibrosis, malignant infiltration, infection, drugs1
Shortened lifespan
Immune
ITP, drugs1, connective tissue disorders, antiphospholipid antibody syndrome, infection, post-transfusion purpura, neonatal alloimmune thrombocytopenia
Non-immune
DIC, thrombotic thrombocytopenic purpura
Sequestration
Hypersplenism, cardiopulmonary bypass surgery
Dilution
Massive blood transfusion
Failure of marrow production. The bone marrow failure of haematological disease (e.g. aplastic anaemia, leukaemia) usually causes pancytopenia. However, thrombocytopenia may be the only sign of intrinsic marrow disease or marrow suppression associated with infection or chemotherapy.
Shortened lifespan. Platelets can be destroyed in the circulation. The most common mechanism is an immunological reaction in clinical syndromes such as immune thrombocytopenia.
Sequestration. Splenomegaly can cause low platelet counts because of pooling in the enlarged organ. The spleen is not necessarily massively enlarged.
Dilution. Normal platelets are diluted by massive blood transfusion.
Thrombocytopenia
WordPress theme by UFO themes