Thrombocytopenia

Definition
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.

 

Clinical picture:
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).

 

Occurrence:
Thrombocytopenia can be etiologically subdivided into four groups.

1. Decreased production a) General bone marrow insufficiency:
- Leukemia
- Myelodysplastic syndromes
- Myelofibrosis
- Megaloblastic anemia
- Bone marrow infiltration by lymphoma or solid tumor metastases
b) Selective megakaryocytic hypoplasia
- Drugs, alcohol, chemicals
- Radiation exposure
- Viral infections
c) Inherited
- May-Hegglin anomaly
- Wiskott-Aldrich syndrome
- Bernard-Soulier syndrome and others
2. Shortened survival span
a) Immunologic
- Autoantibodies (ITP, CLL, connective tissue diseases, e.g. lupus erythematosus, HIV)
- Alloantibodies (after transfusions, neonatal)
b) Drug-induced
c) Microangiopathic hemolytic anemia
- TTP, hemolytic-uremic syndrome (HUS), disseminated intravascular coagulation (DIC)
3. Sequestration
Various causes of splenomegaly, e.g. congestive splenomegaly in portal hypertension
4. Hemodilution
After massive blood transfusion