Definition & Etiology
Definition
Platelet abnormalities: disorders affecting platelet count, classified as:
- Thrombocytopenia: platelet count <150 x 10^9/L
- Thrombocytosis: platelet count >400 x 10^9/L
Prevalence
Normal platelet range: 150-400 x 10^9/L
Etiology
Thrombocytosis:
Primary causes:
- Polycythaemia rubra vera
- Essential thrombocytosis
- Chronic myelogenous leukaemia
- Primary myelofibrosis
- Unspecified myeloproliferative disorder
- Myelodysplastic syndrome
Secondary causes:
- Drug-induced: corticosteroids
- Chronic inflammation: RA, SLE
- Antiphospholipid syndrome (most common secondary cause)
- Systemic infections: endocarditis, pericarditis
- Specific cancers: lung, colorectal, endometrial, oesophageal, gastric
- Splenectomy
- Hyposplenism
- Bleeding
- Trauma
Surgery
Thrombocytopenia causes:
- Decreased production (Bone marrow disruption)
- Malignancies
- Myelofibrosis
- Sarcoidosis
- Nutritional deficiencies
- Congenital disorders
- Increased destruction:
- ITP
- TTP
- DIC
- HIT
- Drug-induced: NSAIDs, penicillin, quinine, quinidine
- HELLP syndrome
- Increased sequestration:
– Splenomegaly due to Portal hypertension secondary to:
Heart failure
Liver cirrhosis
Hepatic vein thrombosis
Vena cava thrombosis
- Others:
- Dilutional: pregnancy, post blood transfusion
- Cancer-related: bone marrow suppression, chemotherapy, radiotherapy