ToolsCalculators
4Ts score for heparin-induced thrombocytopenia
Pre-test probability of HIT.
4Ts score for heparin-induced thrombocytopenia
Thrombocytopenia (magnitude of platelet fall)
Timing of platelet fall
Thrombosis or other sequelae
Other cause for thrombocytopenia
Result0 points
Low pre-test probability of HIT (about ~3%). A low score has a high negative predictive value.
- Probability
- Low
- Approx. HIT likelihood
- ~3%
When to use
- Estimating the likelihood of heparin-induced thrombocytopenia before ordering immunoassays or functional testing.
Formula
0-2 points each for Thrombocytopenia, Timing, Thrombosis and oTher cause. Range 0-8; low 0-3, intermediate 4-5, high 6-8.
Pearls and pitfalls
- A low score reliably excludes HIT and usually avoids the need to stop heparin.
- Confirm intermediate/high scores with a functional assay.