Interactive 4Ts Score calculator for [[Heparin-induced thrombocytopenia|HIT]]. Requires the calculator gadget.
Usage: {{HIT 4Ts Calculator}}
4Ts Score for HIT
4Ts Score for Heparin-Induced Thrombocytopenia
| Criteria |
0 Points |
1 Point |
2 Points
|
| Thrombocytopenia
|
1 <30% fall or nadir <10
|
30–50% fall or nadir 10–19
|
>50% fall and nadir ≥20
|
| Timing of platelet fall
|
1 <4 days without recent heparin
|
Consistent but unclear; or fall after day 10
|
5–10 days; or ≤1 day if recent heparin
|
| Thrombosis or other sequelae
|
1 None
|
Progressive/recurrent or suspected
|
Confirmed new thrombosis or skin necrosis
|
| Other causes for thrombocytopenia
|
1 Definite other cause present
|
Possible other cause
|
No other cause apparent
|
| 4Ts Score
|
/ 8
|
Interpretation — Pretest Probability for HIT
| 0–3
|
Low probability (~5% risk of HIT). HIT antibody testing usually not needed.
|
| 4–5
|
Intermediate probability (~14% risk). Send HIT antibody; consider alternative anticoagulation.
|
| 6–8
|
High probability (~64% risk). Start alternative anticoagulant; send confirmatory testing.
|
References
- Lo GK, et al. Evaluation of pretest clinical score (4 Ts) for the diagnosis of heparin-induced thrombocytopenia. J Thromb Haemost. 2006;4(4):759-765. PMID 16634744.
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