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4T Score (HIT)

4T Score (HIT): calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.

ℹ Reference calculation based on the published method. It does not replace a clinical examination or a doctor's decision.

4T Score (HIT)

Thrombocytopenia: 2 = fall >50% and nadir ≥20; 1 = 30–50% or nadir 10–19; 0 = <30% or nadir <10
Timing: 2 = day 5–10, or ≤1 day with heparin in the prior 30 days; 1 = after day 10, unclear, or heparin 30–100 days ago; 0 = <4 days without recent heparin
Thrombosis: 2 = new confirmed, skin necrosis, systemic reaction to bolus; 1 = progressive or recurrent, non-necrotizing skin lesions, suspected; 0 = none
Other causes of thrombocytopenia: 2 = none; 1 = possible; 0 = definite
4Ts score
5
A probability estimate, not a diagnosis — the physician decides4T Score (HIT): calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.
Probability of HIT
Intermediate
HIT rate in this group
≈ 14 %

More about: 4T Score (HIT)

What it calculates

The “4T Score (HIT)” calculator computes 4Ts score from 4 parameters: thrombocytopenia: 2 = fall >50% and nadir ≥20; 1 = 30–50% or nadir 10–19; 0 = <30% or nadir <10, timing: 2 = day 5–10, or ≤1 day with heparin in the prior 30 days; 1 = after day 10, unclear, or heparin 30–100 days ago; 0 = <4 days without recent heparin, thrombosis: 2 = new confirmed, skin necrosis, systemic reaction to bolus; 1 = progressive or recurrent, non-necrotizing skin lesions, suspected; 0 = none, other causes of thrombocytopenia: 2 = none; 1 = possible; 0 = definite.

Used by professionals and patients to assess health metrics, dosages, and risks.

Example calculation

With parameters Thrombocytopenia: 2 = fall >50% and nadir ≥20; 1 = 30–50% or nadir 10–19; 0 = <30% or nadir <10 = 2, Timing: 2 = day 5–10, or ≤1 day with heparin in the prior 30 days; 1 = after day 10, unclear, or heparin 30–100 days ago; 0 = <4 days without recent heparin = 2, Thrombosis: 2 = new confirmed, skin necrosis, systemic reaction to bolus; 1 = progressive or recurrent, non-necrotizing skin lesions, suspected; 0 = none = 0, Other causes of thrombocytopenia: 2 = none; 1 = possible; 0 = definite = 1 the result is 5 (A probability estimate, not a diagnosis — the physician decides).

How to use

  1. Enter thrombocytopenia: 2 = fall >50% and nadir ≥20; 1 = 30–50% or nadir 10–19; 0 = <30% or nadir <10, timing: 2 = day 5–10, or ≤1 day with heparin in the prior 30 days; 1 = after day 10, unclear, or heparin 30–100 days ago; 0 = <4 days without recent heparin, thrombosis: 2 = new confirmed, skin necrosis, systemic reaction to bolus; 1 = progressive or recurrent, non-necrotizing skin lesions, suspected; 0 = none and other causes of thrombocytopenia: 2 = none; 1 = possible; 0 = definite — each field above is adjustable with a slider.
  2. 4Ts score is calculated automatically as you type.
  3. Check the worked example below to see the formula applied to real numbers.
  4. Copy the result or bookmark this calculator.

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FAQ

How is BMI calculated?
BMI = weight (kg) / height (m)². Example: 70 kg / (1.75 m)² = 22.9. The WHO normal range is 18.5–24.9; below that is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes may show a high BMI with low body fat. It is also less reliable for teenagers, pregnant people, older adults, and very tall or short individuals.
What are the BMI categories?
Underweight: below 18.5. Normal: 18.5–24.9. Overweight: 25–29.9. Obese class I: 30–34.9; class II: 35–39.9; class III: 40+.
What is a better measure than BMI?
Body fat percentage, waist-to-height ratio (aim for under 0.5), and waist circumference give a clearer picture of health than BMI alone.

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