Thrombocytopenia
| Condition | Notes | ||
| ITP | due to antibodies made after viral infection. mucocutaneous bleeding (epistaxis, hematuria, ecchymosis, petechiae) | ↓PLT ↑BT (normal PT & PTT) normal/ slightly ↑ size | observe only if mild (cutaneous bleeds, PLT ≥30,000) Steroids/IVG/anti-D if severe (bleeding or PLT<30,000) Test for HCV & HIV |
| TTP | hereditary/ acquired Antibody against ADAMTS13 → uncleared vWF multimers → PLT trapping & activation fever, neuro sx, renal failure | ↓PLT with hemolysis (↑LDH, ↓haptoglobin, ↓RBC, schistocytes) ↑BT (normal PT & PTT) | plasma exchange/ steroids/ rituximab replenishes ADAMTS13 & removes antibodies |
| HIT-1 | heparin activates PLT directly → ↓PLT count within the first 2 days of use. Then PLT normalizes. Milder than HIT-2 | ||
| HIT-2 | auto-immune: antibodies against PLT factor 4 (PF4) complex with heparin. Seen 5-10 days after starting heparin with ≥50% drop in PLT. Massive clots → stroke/ PE/ Limb ischemia. | Serotonin release assay | Stop all heparin. Argatroban (direct thrombin inhibitor) or fondaparinux. Once PLT>150,000, switch to warfarin |
| DIC | ↑tissue factor (TF) from endothelial damage from TF release by cancers/ etc → over activated coagulation cascade → consumptive coagulopathy. Lipopolysaccharide (sepsis) →DIC | ↑PT, ↑PTT, ↓PLT, ↓fibrinogen, ↑D-dimer | treat cause appropriate blood products (eg massive bleed gets pRBC, PLT, FFP) |
| Hemophilia A | XR, factor 8 | ↑PTT (normal PLT, PT) | Desmopressin Factor 8 replacement; if inhibitor present give activated factor 7 or activated prothrombin complex |
| Hemophilia B | XR, factor 9 | ↑PTT (normal PLT, PT) | factor 9 replacement |
| Hemophilia C | factor 11 | ||
| vWD | factor 8 | ||
| Vitamin K deficiency | factor 2,7,9, 10, protein C&S | ↑PT first then ↑PTT if severe | Vitamin K FFP |
| Factor V Leiden mutation | most common hereditary hypercoagulability | ||
| Prothrombin mutation | 2nd most common | ||
| Antithrombin deficiency | inherited: rare acquired: DIC, cirrhosis, nephrotic syndrome | ||
| Protein C/S deficiency | ↓inactivation of factor Va & VIIIa warfarin-induced skin necrosis (protein C only) |
