HAT Score (hemorrhage after thrombolysis)
Hemorrhage After Thrombolysis (HAT) score (Lou 2008): estimates symptomatic-ICH risk after IV thrombolysis (0-5).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Baseline NIHSS
- 22
- Baseline CT hypodensity extent
- > 1/3 of the MCA territory (+2)
- History of diabetes or admission glucose > 200 mg/dL
- Yes
Result: HAT 5/5: symptomatic ICH risk after thrombolysis ~44%.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Risk
- symptomatic ICH 2% at 0, 5% at 1, 10% at 2, 15% at 3, and 44% above 3.
What you enter
- Baseline NIHSS
- Baseline CT hypodensity extent
- History of diabetes or admission glucose > 200 mg/dL
How this is calculated
- Components
- baseline NIHSS (< 15 = 0, 15-20 = +1, > 20 = +2), CT hypodensity (none / <= 1/3 MCA / > 1/3 MCA = 0/+1/+2), and diabetes or glucose > 200 mg/dL (+1), summed 0-5.
Lou M, Safdar A, Mehdiratta M, et al. The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis. Neurology. 2008;71(18):1417-1423. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.