Heparin-Induced Thrombocytopenia (HIT) Pathway

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

🎓 Want to practice? Do a case challenge with this pathway → (get a case, choose management step by step, scored).

Full pathway

1. [Decision] 4T score
   4T score (thrombocytopenia/timing/thrombosis/other cause)? (HIT: anti-PF4-heparin antibodies activate platelets → thrombocytopenia + paradoxical thrombosis (venous > arterial, not bleeding). Each 4T item 0–2: degree of platelet fall (>50% with nadir ≥20 = 2), timing (5–10 days after exposure or recent exposure <1 day = 2), thrombosis (new = 2), other cause (none = 2). Total 0–3 low, 4–5 intermediate, 6–8 high.)
   • ≥4 (intermediate-high) → ≥4 → stop heparin + switch agent
   • 0–3 (low) → 0–3 (low)
2. [End] 0–3 (low)
   HIT unlikely — do not test antibodies, do not stop heparin, evaluate other causes of thrombocytopenia; continue/resume heparin as needed.
3. [End] ≥4 → stop heparin + switch agent
   1) Immediately stop all heparin (including flushes, LMWH, heparin-coated catheters). 2) Switch to non-heparin anticoagulation (argatroban, bivalirudin, fondaparinux or a DOAC) — anticoagulate even without thrombosis (high thrombotic risk). 3) Test anti-PF4/heparin antibodies (ELISA), confirm positives with a functional assay (serotonin release). 4) No platelet transfusion (prothrombotic, unless severe bleeding); no warfarin until platelets recover (>150 x10e9) (to prevent venous limb gangrene), overlapping with non-heparin anticoagulation. 5) Doppler screening for thrombosis.

Source guidelines & references

• 4T score (Warkentin); ASH HIT management guideline

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

Other pathways