**Decreased platelet production**
1. Pancytopenia
2. Primary malignancy e.g. leukemia
3. Bone marrow infiltration e.g. neuroblastoma
4. Bone marrow failure e.g aplastic anemia
5. Viral infections e.g. HIV
6. Cytotoxic drugs, radiation
7. Selective ineffective thrombopoiesis
8. Rare congenital defects e.g thrombocytopenia-absent radius (TAR)
syndrome, Wiskott Aldrich syndrome, congenital amegakaryocytic
thrombocytopenia and giant platelet disorders (e.g Bernard-Soulier
syndrome)
Viral infections e.g EBV, CMV, parvovirus
**Increased platelet consumption**
1. Idiopathic thrombocytopenic purpura (ITP) (most common cause
of thrombocytopenia in children)
2. Neonatal alloimmune thrombocytopenia (NAIT)
3. Collagen-vascular and autoimmune diseases e.g. SLE Viruses e.g. HIV Drug-induced e.g. heparin
4. Disseminated intravascular coagulation (DIC)
5. Hemolytic-uremic syndrome (HUS)
6. Sepsis
7. Thrombotic thrombocytopenic purpura (TTP)
**Platelet sequestration**
1. Hypersplenism
2. Infection
3. Inflammation
4. Congestion
5. Red cell disorders
6. Storage diseases
**Dilutional loss**
- Recent massive blood transfusion
