Thrombocytopenia

Definition

<150,000 platelets/µL

Transfusion Criteria

1. <50,000 & severe bleed or invasive procedure
2. <20,000 & fever, petechia, or infection
3. <5,000-10,000 --> always?
   1. Usually ineffective in ITP (give only in severe bleed; best after IVIg)
   2. DIC may worsen with platlet tranfusion
   3. Likely contraindicated in TTP

Causes

1. Decreased production
   1. Marrow infiltration (tumor or infection)
   2. Viral infections (rubella, HIV)
   3. Drugs
      1. Heparin, sulfa abx, ETOH, ASA, thiazides/furosemide
   4. Radiation
   5. Vitamin B12 and/or folate deficiency
2. Increased platelet destruction
   1. ITP
   2. TTP
   3. HUS
   4. DIC
   5. Viral infections (HIV, mumps, varicella, EBV)
   6. Drugs (heparin, protamine)
3. Platelet loss
   1. Excessive hemorrhage
   2. Hemodialysis, extracorporeal circulation
4. Splenic sequestration
   1. Sickle cell disease, cirrhosis

Pediatrics

1 unit platelets per 5kg body weight will raise count by 50k

Source

Tintinalli