Thrombocytopenia is present if the platelet count decreases below x 109/L. Before the diagnosis of thrombocytopenia can be established, pseudo-thrombocytopenia must always be excluded.
Thrombocytopenia usually causes spontaneous bleeding at values under 20 x 109/L, providing that no additional platelet defect is present. Skin and mucous membrane bleeding are typical (petechiae and ecchymoses).
Thrombocytopenia can be etiologically subdivided into four groups.
|1. Decreased production||a) General bone marrow insufficiency:
- Myelodysplastic syndromes
- Megaloblastic anemia
- Bone marrow infiltration by lymphoma or solid tumor metastases
b) Selective megakaryocytic hypoplasia
- Drugs, alcohol, chemicals
- Radiation exposure
- Viral infections
- May-Hegglin anomaly
- Wiskott-Aldrich syndrome
- Bernard-Soulier syndrome and others
2. Shortened survival span
- Autoantibodies (ITP, CLL, connective tissue diseases, e.g. lupus erythematosus, HIV)
- Alloantibodies (after transfusions, neonatal)
c) Microangiopathic hemolytic anemia
- TTP, hemolytic-uremic syndrome (HUS), disseminated intravascular coagulation (DIC)
|Various causes of splenomegaly, e.g. congestive splenomegaly in portal hypertension|
|After massive blood transfusion|