This handout is for heparin-induced thrombocytopenia (hit) — 4ts + non-heparin anticoagulation. Your care team identified this based on: platelet drop >50% (or to <150k) days 5-10 of heparin exposure — calculate 4ts (ash 2018 pmid 30482768).
Other reasons your team may use this plan: new arterial or venous thrombosis on heparin (dvt/pe/limb ischemia/cva/mi) — high 4ts probability (ash 2018 pmid 30482768); skin necrosis at heparin sc injection site — pathognomonic for hit regardless of platelet count (ash 2018); acute anaphylactoid reaction (rigors, hypotension, dyspnea) minutes after iv heparin bolus — possible severe hit.
Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.
| Medication | Starting dose | How | When | What it does |
|---|---|---|---|---|
| argatroban | 2 mcg/kg/min IV continuous (reduce to 0.5 mcg/kg/min if significant hepatic dysfunction Child-Pugh B/C); titrate to aPTT 1.5-3x baseline (or anti-IIa target) | IV | continuous infusion | ARG-911 (Lewis Circulation 2001 PMID 11294800) — argatroban significantly reduced composite of death, amputation, new thrombosis vs historical controls in HIT and HITT. Hepatic clearance allows safe use in renal failure; dose-reduce to 0.5 mcg/kg/min if Child-Pugh B/C. |
Plan: Non-heparin anticoagulation for acute HIT (intermediate/high 4Ts) — ASH 2018 PMID 30482768
Call 911 or go to the nearest emergency room right away if you have:
Duration: isolated HIT (no thrombosis) → minimum 4 weeks of anticoagulation (until platelet recovery + several days stable platelets); HITT (HIT with thrombosis) → at least 3 months — ASH 2018. Long-term: lifelong heparin avoidance documented in chart and medical-alert ID; HIT antibodies decline over ~100 days; if heparin re-exposure required emergently (cardiac surgery) AND antibodies still positive → use bivalirudin intraop; if antibodies negative ≥100 d post-event → heparin may be used short-course (cardiac surgery, hemodialysis) with close monitoring. Hematology follow-up at 1 mo, 3 mo, and 1 year; consider switch from warfarin to DOAC once HIT resolved and patient stable — ASH 2018
Guideline: ASH 2018 HIT guidelines (Cuker Blood Adv 2018) + 4Ts validation (Lo JTH 2006) + ARG-911 (Lewis Circulation 2001) + autoimmune HIT review (Greinacher JTH 2017)