🩸 4Ts Score (Heparin-Induced Thrombocytopenia)
Estimate the probability of heparin-induced thrombocytopenia (HIT) with the 4Ts score.
4Ts Score (Heparin-Induced Thrombocytopenia)
Thrombocytopenia
Timing of platelet fall
Thrombosis or sequelae
Other cause of thrombocytopenia
When to use
Decide whether to stop heparin and send HIT antibody testing.
How it works
Four domains (Thrombocytopenia, Timing, Thrombosis, oTher cause) each 0–2. 0–3 low, 4–5 intermediate, 6–8 high probability.
Key points
- Low score (0–3) has a high negative predictive value — HIT is unlikely.
- Intermediate/high scores warrant stopping heparin and immunoassay/functional testing.
- Do not wait for testing to switch anticoagulant if probability is high.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.