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NAFLD activity score

NAS

Return the Kleiner 2005 NAFLD activity score (NAS) as the sum of three caller-assigned integer components (steatosis 0-3, lobular_inflammation 0-3, ballooning 0-2). Max 8. Does not return NASH diagnostic bands.

LIVE $0.005 USDC GET /api/calc/nafld_nas

Markdown: /docs/nafld-nas.md · Canonical: https://magentlab.com/docs/nafld-nas

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

What it computes

When to use

When an agent already has Kleiner 2005 NAS component points and needs the published total. magent does not read histology or assign grades from a narrative, and does not apply NASH diagnostic cutoffs.

When not to use

Not a medical device and not a NASH diagnosis, biopsy, or treatment order. magent does not read histology.
Inputs are caller-assigned Kleiner 2005 point integers (steatosis 0-3, lobular_inflammation 0-3, ballooning 0-2), not percent fat, foci counts, or a fibrosis stage. Paper bins: steatosis <5% / 5–33% / >33–66% / >66%; lobular inflammation none / <2 foci per 200× / 2–4 / >4; ballooning none / few / many or prominent.
Kleiner 2005 stages fibrosis separately. Fibrosis is not in NAS and is not an input to this tool.
Kleiner 2005 reported NAS ≥5 correlated with NASH in that study; that is not a diagnostic algorithm. magent returns score and max_score only and does not apply NASH diagnostic bands.

Formula

NAS = steatosis (integer 0-3) + lobular_inflammation (integer 0-3) + ballooning (integer 0-2); Kleiner 2005 caller-assigned; max 8; fibrosis is not in NAS; no NASH diagnostic bands

Citation

Title: Design and validation of a histological scoring system for nonalcoholic fatty liver disease.
Authors: Kleiner DE, Brunt EM, Van Natta M, et al.
Source: Hepatology. 2005;41(6):1313-1321
DOI: 10.1002/hep.20701

Worked example

All zeros

Given: ballooning=0lobular_inflammation=0steatosis=0

steatosis 0 + lobular_inflammation 0 + ballooning 0
Score = 0 (max 8). No NASH band.

Maximum published score

Given: ballooning=2lobular_inflammation=3steatosis=3

steatosis 3 + lobular_inflammation 3 + ballooning 2
Score = 8 (max 8). No NASH band.

Also searched as

NAFLD activity score
NAS
Kleiner NAS
Kleiner 2005 NAS
NASH CRN NAS
NAFLD Activity Score
NAS histology score
Kleiner NAFLD activity score

Try

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

/api/calc/nafld_nas?steatosis=0&lobular_inflammation=0&ballooning=0

Full URL: https://api.magentlab.com/api/calc/nafld_nas?steatosis=0&lobular_inflammation=0&ballooning=0

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/nafld_nas?steatosis=0&lobular_inflammation=0&ballooning=0"

Parameters

Name	Type	Required	Description
`steatosis`	integer	required	Caller-assigned Kleiner 2005 steatosis points 0-3 (paper bins: 0 <5%; 1 5–33%; 2 >33–66%; 3 >66%). magent does not read histology.
`lobular_inflammation`	integer	required	Caller-assigned Kleiner 2005 lobular inflammation points 0-3 (paper bins: 0 none; 1 <2 foci/200×; 2 2–4 foci/200×; 3 >4 foci/200×). magent does not read histology.
`ballooning`	integer	required	Caller-assigned Kleiner 2005 hepatocellular ballooning points 0-2 (paper bins: 0 none; 1 few; 2 many/prominent). magent does not read histology.

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/nafld_nas 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": [
    {
      "ballooning": "0",
      "lobular_inflammation": "0",
      "steatosis": "0"
    },
    {
      "ballooning": "0",
      "lobular_inflammation": "0",
      "steatosis": "0"
    }
  ]
}

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/nafld_nas",
  "items": [
    {
      "components": [
        {
          "value": 0,
          "factor": "steatosis",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "lobular_inflammation",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ballooning",
          "points": 0,
          "present": true
        }
      ],
      "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": "Kleiner DE, Brunt EM, Van Natta M, et al.",
        "doi": "10.1002/hep.20701",
        "id": "kleiner-2005",
        "pmid": "15915461",
        "source": "Hepatology. 2005;41(6):1313-1321",
        "title": "Design and validation of a histological scoring system for nonalcoholic fatty liver disease."
      },
      "formula": "nafld_nas",
      "formula_expression": "NAS = steatosis (integer 0-3) + lobular_inflammation (integer 0-3) + ballooning (integer 0-2); Kleiner 2005 caller-assigned; max 8; fibrosis is not in NAS; no NASH diagnostic bands",
      "max_score": 8,
      "score": 0,
      "ballooning": 0,
      "lobular_inflammation": 0,
      "steatosis": 0
    },
    {
      "components": [
        {
          "value": 0,
          "factor": "steatosis",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "lobular_inflammation",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "ballooning",
          "points": 0,
          "present": true
        }
      ],
      "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": "Kleiner DE, Brunt EM, Van Natta M, et al.",
        "doi": "10.1002/hep.20701",
        "id": "kleiner-2005",
        "pmid": "15915461",
        "source": "Hepatology. 2005;41(6):1313-1321",
        "title": "Design and validation of a histological scoring system for nonalcoholic fatty liver disease."
      },
      "formula": "nafld_nas",
      "formula_expression": "NAS = steatosis (integer 0-3) + lobular_inflammation (integer 0-3) + ballooning (integer 0-2); Kleiner 2005 caller-assigned; max 8; fibrosis is not in NAS; no NASH diagnostic bands",
      "max_score": 8,
      "score": 0,
      "ballooning": 0,
      "lobular_inflammation": 0,
      "steatosis": 0
    }
  ]
}

Response

Field	Type	Description
`formula`	string	nafld_nas
`formula_expression`	string	Exact expression used
`score`	integer	Kleiner 2005 NAS points 0-8
`max_score`	integer	Always 8
`steatosis`	integer	Caller-assigned steatosis points 0-3
`lobular_inflammation`	integer	Caller-assigned lobular inflammation points 0-3
`ballooning`	integer	Caller-assigned ballooning points 0-2
`components`	array	Per-component caller-assigned points
`citation`	object	Kleiner et al. Hepatology 2005 citation
`disclaimer`	string	Not a medical device

Example JSON

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

{
  "components": [
    {
      "value": 0,
      "factor": "steatosis",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "lobular_inflammation",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "ballooning",
      "points": 0,
      "present": true
    }
  ],
  "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": "Kleiner DE, Brunt EM, Van Natta M, et al.",
    "doi": "10.1002/hep.20701",
    "id": "kleiner-2005",
    "pmid": "15915461",
    "source": "Hepatology. 2005;41(6):1313-1321",
    "title": "Design and validation of a histological scoring system for nonalcoholic fatty liver disease."
  },
  "formula": "nafld_nas",
  "formula_expression": "NAS = steatosis (integer 0-3) + lobular_inflammation (integer 0-3) + ballooning (integer 0-2); Kleiner 2005 caller-assigned; max 8; fibrosis is not in NAS; no NASH diagnostic bands",
  "max_score": 8,
  "score": 0,
  "ballooning": 0,
  "lobular_inflammation": 0,
  "steatosis": 0
}

Client errors (HTTP 400)

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

HTTP	Code	When
400	`invalid_nafld_nas`	steatosis must be an integer 0-3, lobular_inflammation an integer 0-3, and ballooning an integer 0-2 (Kleiner 2005 NAS). 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

FIB-4 — Compute the FIB-4 fibrosis index from age, AST, ALT, and platelets.
NAFLD fibrosis score — Compute the Angulo 2007 NAFLD fibrosis score from age, BMI, IFG/diabetes, AST, ALT, platelets, and albumin.
BARD — Sum the Harrison 2008 BARD score (BMI ≥28, AST/ALT ≥0.8, diabetes) and return low (0–1) or high (2–4).
SAFE score — Compute the Sripongpun 2023 steatosis-associated fibrosis estimator (SAFE) from age, caller-supplied BMI, diabetes, AST, ALT, globulin in g/dL, and platelets.

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.