# FNI

FNI

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/fni`
HTML: https://magentlab.com/docs/fni
Markdown: https://magentlab.com/docs/fni.md

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

## What it computes

Compute the Tavaglione 2023 fibrotic NASH index (FNI) from AST, HbA1c, and HDL cholesterol as a score for fibrotic nonalcoholic steatohepatitis.

## When to use

When an agent needs published Tavaglione 2023 FNI arithmetic and must not invent FIB-4, NAFLD fibrosis, SAFE, or BARD cutoffs or a biopsy result.

## When not to use

- Not a medical device. Not a diagnosis and not a biopsy. FNI bands are published rule-out and rule-in cut-points, not histology.
- Tavaglione 2023 FNI only. Not FIB-4, not the NAFLD fibrosis score, not SAFE, and not BARD.
- HDL must be exactly one of hdl_mg_dl (5-150) or hdl_mmol_l (0.1-3.9). mmol/L converts as mg/dL = mmol/L * 38.67. magent does not assay AST, HbA1c, or HDL.

## Formula

```
FNI = e^x / (1+e^x) where x = -10.33 + 2.54*ln(AST U/L) + 3.86*ln(HbA1c %) - 1.66*ln(HDL mg/dL) (natural log)
```

## Citation

[Development and Validation of a Score for Fibrotic Nonalcoholic Steatohepatitis](https://doi.org/10.1016/j.cgh.2022.03.044)
Tavaglione F, Jamialahmadi O, De Vincentis A, et al.
Clin Gastroenterol Hepatol. 2023;21(6):1523-1532.e1
DOI: [10.1016/j.cgh.2022.03.044](https://doi.org/10.1016/j.cgh.2022.03.044)

## Worked example

### AST 40 U/L, HbA1c 5.5%, HDL 50 mg/dL

Given: `a1c_percent=5.5, ast_u_l=40, hdl_mg_dl=50`

1. x = -10.33 + 2.54*ln(40) + 3.86*ln(5.5) - 1.66*ln(50) = -0.8739
2. FNI = e^x / (1+e^x) = 0.2944
3. 0.10 < 0.2944 < 0.33 → fni_band gt_0_10_lt_0_33


## Also searched as

- fibrotic NASH index
- FNI score
- Tavaglione FNI
- fibrotic nonalcoholic steatohepatitis
- NASH AST HbA1c HDL score
- fibrotic NASH
- FNI liver score

## Parameters

- `ast_u_l` (number, required): Aspartate aminotransferase in U/L (1-10000).
- `a1c_percent` (number, required): HbA1c in percent (4-15). magent does not convert from eAG.
- `hdl_mg_dl` (number, optional): HDL cholesterol in mg/dL (5-150). Provide this or hdl_mmol_l, not both. Used in the natural-log term.
- `hdl_mmol_l` (number, optional): HDL cholesterol in mmol/L (0.1-3.9). Converted as mg/dL = mmol/L * 38.67. Provide this or hdl_mg_dl, not both.

## 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.

Method: `POST /api/calc/fni`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: 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:

```json
{
  "items": [
    {
      "a1c_percent": "5.5",
      "ast_u_l": "40",
      "hdl_mg_dl": "50"
    },
    {
      "a1c_percent": "5.5",
      "ast_u_l": "40",
      "hdl_mg_dl": "50"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/fni

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/fni",
  "items": [
    {
      "x": -0.8739,
      "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": "Tavaglione F, Jamialahmadi O, De Vincentis A, et al.",
        "doi": "10.1016/j.cgh.2022.03.044",
        "id": "tavaglione-2023",
        "pmid": "35421583",
        "source": "Clin Gastroenterol Hepatol. 2023;21(6):1523-1532.e1",
        "title": "Development and Validation of a Score for Fibrotic Nonalcoholic Steatohepatitis"
      },
      "formula": "fni",
      "formula_expression": "FNI = e^x / (1+e^x) where x = -10.33 + 2.54*ln(AST U/L) + 3.86*ln(HbA1c %) - 1.66*ln(HDL mg/dL) (natural log)",
      "ast_u_l": 40.0,
      "a1c_percent": 5.5,
      "fni": 0.2944,
      "fni_band": "gt_0_10_lt_0_33",
      "hdl_mg_dl": 50.0,
      "hdl_unit": "mg_dl"
    },
    {
      "x": -0.8739,
      "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": "Tavaglione F, Jamialahmadi O, De Vincentis A, et al.",
        "doi": "10.1016/j.cgh.2022.03.044",
        "id": "tavaglione-2023",
        "pmid": "35421583",
        "source": "Clin Gastroenterol Hepatol. 2023;21(6):1523-1532.e1",
        "title": "Development and Validation of a Score for Fibrotic Nonalcoholic Steatohepatitis"
      },
      "formula": "fni",
      "formula_expression": "FNI = e^x / (1+e^x) where x = -10.33 + 2.54*ln(AST U/L) + 3.86*ln(HbA1c %) - 1.66*ln(HDL mg/dL) (natural log)",
      "ast_u_l": 40.0,
      "a1c_percent": 5.5,
      "fni": 0.2944,
      "fni_band": "gt_0_10_lt_0_33",
      "hdl_mg_dl": 50.0,
      "hdl_unit": "mg_dl"
    }
  ]
}
```

## Response fields

- `formula` (string): fni
- `formula_expression` (string): Exact Tavaglione 2023 expression (natural log; HDL in mg/dL)
- `ast_u_l` (number): AST in U/L
- `a1c_percent` (number): HbA1c in percent
- `hdl_mg_dl` (number): HDL cholesterol used in mg/dL (after mmol/L conversion when supplied)
- `hdl_unit` (string): Caller HDL unit used: mg_dl or mmol_l
- `x` (number): Linear predictor x, 4 decimals
- `fni` (number): FNI probability, 4 decimals
- `fni_band` (string): Published Tavaglione 2023 cut-points on the rounded FNI: lte_0_10 (rule-out; FNI ≤ 0.10), gt_0_10_lt_0_33 (indeterminate; 0.10 < FNI < 0.33), gte_0_33 (rule-in; FNI ≥ 0.33). Not a biopsy.
- `citation` (object): Tavaglione Clin Gastroenterol Hepatol 2023 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "x": -0.8739,
  "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": "Tavaglione F, Jamialahmadi O, De Vincentis A, et al.",
    "doi": "10.1016/j.cgh.2022.03.044",
    "id": "tavaglione-2023",
    "pmid": "35421583",
    "source": "Clin Gastroenterol Hepatol. 2023;21(6):1523-1532.e1",
    "title": "Development and Validation of a Score for Fibrotic Nonalcoholic Steatohepatitis"
  },
  "formula": "fni",
  "formula_expression": "FNI = e^x / (1+e^x) where x = -10.33 + 2.54*ln(AST U/L) + 3.86*ln(HbA1c %) - 1.66*ln(HDL mg/dL) (natural log)",
  "ast_u_l": 40.0,
  "a1c_percent": 5.5,
  "fni": 0.2944,
  "fni_band": "gt_0_10_lt_0_33",
  "hdl_mg_dl": 50.0,
  "hdl_unit": "mg_dl"
}
```

## Errors

- HTTP 400 `invalid_ast`: ast_u_l must be a number from 1 to 10000 Returned before settlement; you are not charged.
- HTTP 400 `invalid_a1c`: a1c_percent must be a number from 4 to 15 Returned before settlement; you are not charged.
- HTTP 400 `invalid_hdl`: hdl_mg_dl must be a number from 5 to 150, or hdl_mmol_l from 0.1 to 3.9, not both. Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [FIB-4](https://magentlab.com/docs/fib4) — Compute the FIB-4 fibrosis index from age, AST, ALT, and platelets.
- [NAFLD fibrosis score](https://magentlab.com/docs/nafld-fibrosis) — Compute the Angulo 2007 NAFLD fibrosis score from age, BMI, IFG/diabetes, AST, ALT, platelets, and albumin.
- [SAFE score](https://magentlab.com/docs/safe) — Compute the Sripongpun 2023 steatosis-associated fibrosis estimator (SAFE) from age, caller-supplied BMI, diabetes, AST, ALT, globulin in g/dL, and platelets.
- [BARD](https://magentlab.com/docs/bard) — Sum the Harrison 2008 BARD score (BMI ≥28, AST/ALT ≥0.8, diabetes) and return low (0–1) or high (2–4).

## 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.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/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.