HAT score

HAT

Compute the Lou 2008 HAT (Hemorrhage After Thrombolysis) score for symptomatic intracranial hemorrhage after stroke thrombolysis from diabetes or baseline glucose >200 mg/dL, pretreatment NIHSS, and easily visible hypodensity on initial CT.

LIVE $0.005 USDC GET /api/calc/hat

Markdown: /docs/hat.md · Canonical: https://magentlab.com/docs/hat

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

When to use

When an agent has caller-assigned diabetes, baseline glucose, NIHSS, and CT hypodensity and needs the published HAT total and collective symptomatic ICH percents, without inventing NIHSS, CT findings, an equals-1/3 hypodensity band, or unofficial percents.

When not to use

Not a medical device and not a tPA withhold, thrombolysis, or treatment decision.
Derived in intravenous thrombolysis (Lou 2008). It is not a recommendation for or against alteplase.
The caller assigns diabetes mellitus, baseline glucose, NIHSS (0-42), and easily visible hypodensity on initial CT. magent does not examine the patient, assign NIHSS, or read CT.
History of diabetes mellitus OR baseline glucose >200 mg/dL scores 1 (not additive if both). 200.0 mg/dL does not score; 201 does. Glucose is scored in mg/dL; mmol/L converts as mg/dL = mmol/L × 18.
Pretreatment NIHSS <15 scores 0; 15-20 scores 1; >20 scores 2.
Hypodensity is none (0), less_than_third (<1/3 MCA, 1), or greater_than_third (>1/3 MCA, 2). There is no published equals-1/3 category.
Collective symptomatic ICH percents are 2% (0), 5% (1), 10% (2), 15% (3), 44% (>3). Scores 4 and 5 both return 44. magent does not invent other percents.

Formula

HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3

Citation

Title: The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis
Authors: Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M
Source: Neurology. 2008;71(18):1417-1423
DOI: 10.1212/01.wnl.0000330297.58334.dd

Worked example

No diabetes, glucose 6.0 mmol/L, NIHSS 10, no hypodensity

Given: diabetes=falseglucose_mmol_l=6.0hypodensity=nonenihss=10

Diabetes false; glucose 6.0 mmol/L → 108.0 mg/dL (not >200) → 0; NIHSS 10 <15 → 0; hypodensity none → 0
Score = 0 (max 5); collective sICH 2%

All items (score 5)

Given: diabetes=trueglucose_mmol_l=20.0hypodensity=greater_than_thirdnihss=42

Diabetes true (glucose 20.0 mmol/L → 360 mg/dL also >200; not additive) → 1; NIHSS 42 >20 → 2; greater_than_third → 2
Score = 5 (max 5); collective sICH 44%

Also searched as

HAT score
Hemorrhage After Thrombolysis
Lou HAT
HAT thrombolysis hemorrhage
symptomatic ICH HAT
Lou 2008 HAT
post-tPA hemorrhage HAT
HAT NIHSS hypodensity

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/hat?diabetes=false&glucose_mmol_l=6.0&nihss=10&hypodensity=none

Full URL: https://api.magentlab.com/api/calc/hat?diabetes=false&glucose_mmol_l=6.0&nihss=10&hypodensity=none

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/hat?diabetes=false&glucose_mmol_l=6.0&nihss=10&hypodensity=none"

Parameters

Name	Type	Required	Description
`diabetes`	boolean	required	History of diabetes mellitus (Lou 2008). true scores 1 on the diabetes-or-glucose item; not additive with glucose >200 mg/dL.
`glucose_mmol_l`	number	optional	Baseline glucose in mmol/L (2.8-55.5). Provide this or glucose_mg_dl, not both. Converted as mg/dL = mmol/L × 18. Scores 1 on the diabetes-or-glucose item if >200 mg/dL after conversion (200.0 does not).
`glucose_mg_dl`	number	optional	Baseline glucose in mg/dL (50-1000). Provide this or glucose_mmol_l, not both. >200 scores 1 on the diabetes-or-glucose item if diabetes is false; 200.0 does not (Lou 2008).
`nihss`	integer	required	Caller-assigned pretreatment NIH Stroke Scale total (integer 0-42). <15 scores 0; 15-20 scores 1; >20 scores 2 (Lou 2008). magent does not compute NIHSS or examine the patient.
`hypodensity`	string	required · none, less_than_third, greater_than_third	Easily visible hypodensity on initial CT as assigned by the caller (Lou 2008). none scores 0; less_than_third (<1/3 MCA) scores 1; greater_than_third (>1/3 MCA) scores 2. No published equals-1/3 category. magent does not read the CT.

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/hat Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

1 to 25 items. Each item uses the same keys as the GET query parameters.
POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "diabetes": "false",
      "glucose_mmol_l": "6.0",
      "hypodensity": "none",
      "nihss": "10"
    },
    {
      "diabetes": "false",
      "glucose_mmol_l": "6.0",
      "hypodensity": "none",
      "nihss": "10"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/hat",
  "items": [
    {
      "components": [
        {
          "value": 108.0,
          "factor": "diabetes_or_glucose",
          "points": 0,
          "present": false,
          "diabetes": false
        },
        {
          "value": 10,
          "factor": "nihss",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "hypodensity",
          "points": 0,
          "present": false
        }
      ],
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
        "doi": "10.1212/01.wnl.0000330297.58334.dd",
        "id": "lou-2008",
        "pmid": "18955684",
        "source": "Neurology. 2008;71(18):1417-1423",
        "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
      },
      "formula": "hat",
      "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
      "max_score": 5,
      "score": 0,
      "nihss": 10,
      "diabetes": false,
      "glucose_mg_dl": 108.0,
      "hypodensity": "none",
      "sich_percent": 2
    },
    {
      "components": [
        {
          "value": 108.0,
          "factor": "diabetes_or_glucose",
          "points": 0,
          "present": false,
          "diabetes": false
        },
        {
          "value": 10,
          "factor": "nihss",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "hypodensity",
          "points": 0,
          "present": false
        }
      ],
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
        "doi": "10.1212/01.wnl.0000330297.58334.dd",
        "id": "lou-2008",
        "pmid": "18955684",
        "source": "Neurology. 2008;71(18):1417-1423",
        "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
      },
      "formula": "hat",
      "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
      "max_score": 5,
      "score": 0,
      "nihss": 10,
      "diabetes": false,
      "glucose_mg_dl": 108.0,
      "hypodensity": "none",
      "sich_percent": 2
    }
  ]
}

Response

Field	Type	Description
`formula`	string	hat
`formula_expression`	string	Exact expression used
`score`	integer	HAT points 0-5
`max_score`	integer	Always 5
`sich_percent`	number	Lou 2008 collective symptomatic ICH percent: 2 (0), 5 (1), 10 (2), 15 (3), 44 (>3). Scores 4 and 5 both 44.
`diabetes`	boolean	Whether history of diabetes mellitus was assigned
`glucose_mg_dl`	number	Baseline glucose in mg/dL (mmol/L inputs converted ×18)
`nihss`	integer	Caller-assigned NIHSS used for the <15 / 15-20 / >20 points
`hypodensity`	string	none, less_than_third, or greater_than_third
`components`	array	Per-item Lou 2008 points
`citation`	object	Lou 2008 Neurology citation
`disclaimer`	string	Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "components": [
    {
      "value": 108.0,
      "factor": "diabetes_or_glucose",
      "points": 0,
      "present": false,
      "diabetes": false
    },
    {
      "value": 10,
      "factor": "nihss",
      "points": 0,
      "present": false
    },
    {
      "value": "none",
      "factor": "hypodensity",
      "points": 0,
      "present": false
    }
  ],
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
    "doi": "10.1212/01.wnl.0000330297.58334.dd",
    "id": "lou-2008",
    "pmid": "18955684",
    "source": "Neurology. 2008;71(18):1417-1423",
    "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
  },
  "formula": "hat",
  "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
  "max_score": 5,
  "score": 0,
  "nihss": 10,
  "diabetes": false,
  "glucose_mg_dl": 108.0,
  "hypodensity": "none",
  "sich_percent": 2
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP	Code	When
400	`invalid_flag`	boolean clinical flags must be true or false Returned before settlement; you are not charged.
400	`invalid_glucose`	glucose_mg_dl (50-1000) or glucose_mmol_l (2.8-55.5) is required Returned before settlement; you are not charged.
400	`invalid_nihss`	nihss must be an integer from 0 to 42. Returned before settlement; you are not charged.
400	`invalid_hat_hypodensity`	hypodensity must be none, less_than_third, or greater_than_third (Lou 2008). Returned before settlement; you are not charged.
400	`invalid_items`	POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400	`invalid_item_count`	items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400	`invalid_item`	each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

SEDAN — Compute the Strbian 2012 SEDAN score (Sugar, Early infarct signs, (hyper)Dense artery, Age, NIHSS) for symptomatic intracranial hemorrhage after stroke thrombolysis.
DRAGON — Compute the Strbian 2012 DRAGON score (Dense artery / early infarct signs, prestroke mRS, Age, Glucose, Onset-to-treatment, NIHSS) for 3-month outcome after IV thrombolysis-treated ischemic stroke.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
Execution is timeout-bounded and concurrency-capped.
Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.