# SAAG

SAAG

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

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

## What it computes

Compute the Runyon 1992 serum-ascites albumin gradient as serum albumin minus ascites albumin in g/dL, and whether that gradient is >= 1.1 g/dL (portal-hypertension physiology).

## When to use

When an agent needs the published SAAG gradient and must not invent Light-style exudate/transudate rules, a diagnosis of portal hypertension, or peritonitis.

## When not to use

- Not a diagnosis. magent does not diagnose portal hypertension or peritonitis.
- Gradient only. This is not an exudate/transudate Light-style rule for ascites.
- Portal-hypertension physiology is saag_g_dl >= 1.1 after rounding to one decimal; 1.0 is below the cutoff.

## Formula

```
saag_g_dl = albumin_g_dl - ascites_albumin_g_dl
```

## Citation

[The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites](https://doi.org/10.7326/0003-4819-117-3-215)
Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG
Ann Intern Med. 1992;117(3):215-220
DOI: [10.7326/0003-4819-117-3-215](https://doi.org/10.7326/0003-4819-117-3-215)

## Worked example

### Serum 3.5, ascites 2.0

Given: `albumin_g_dl=3.5, ascites_albumin_g_dl=2.0`

1. saag_g_dl = 3.5 - 2.0 = 1.5
2. 1.5 >= 1.1 → portal_hypertension_physiology true


### Serum 3.0, ascites 2.0

Given: `albumin_g_dl=3.0, ascites_albumin_g_dl=2.0`

1. saag_g_dl = 3.0 - 2.0 = 1.0
2. 1.0 is not >= 1.1 → portal_hypertension_physiology false


## Also searched as

- serum-ascites albumin gradient
- SAAG gradient
- ascites albumin gradient
- Runyon SAAG
- serum ascites albumin
- portal hypertension SAAG

## Parameters

- `albumin_g_dl` (number, optional): Serum albumin in g/dL (1-6). Provide this or albumin_g_l, not both.
- `albumin_g_l` (number, optional): Serum albumin in g/L (10-60). Converted as g/dL = g/L / 10. Provide this or albumin_g_dl, not both.
- `ascites_albumin_g_dl` (number, optional): Ascites albumin in g/dL (0.1-6). Provide this or ascites_albumin_g_l, not both. May be lower than serum albumin.
- `ascites_albumin_g_l` (number, optional): Ascites albumin in g/L (1-60). Converted as g/dL = g/L / 10. Provide this or ascites_albumin_g_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/saag`
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": [
    {
      "albumin_g_dl": "3.5",
      "ascites_albumin_g_dl": "2.0"
    },
    {
      "albumin_g_dl": "3.5",
      "ascites_albumin_g_dl": "2.0"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/saag",
  "items": [
    {
      "albumin_g_dl": 3.5,
      "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": "Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG",
        "doi": "10.7326/0003-4819-117-3-215",
        "id": "runyon-1992",
        "source": "Ann Intern Med. 1992;117(3):215-220",
        "title": "The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites"
      },
      "formula": "saag",
      "formula_expression": "saag_g_dl = albumin_g_dl - ascites_albumin_g_dl",
      "ascites_albumin_g_dl": 2.0,
      "portal_hypertension_physiology": true,
      "saag_g_dl": 1.5
    },
    {
      "albumin_g_dl": 3.5,
      "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": "Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG",
        "doi": "10.7326/0003-4819-117-3-215",
        "id": "runyon-1992",
        "source": "Ann Intern Med. 1992;117(3):215-220",
        "title": "The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites"
      },
      "formula": "saag",
      "formula_expression": "saag_g_dl = albumin_g_dl - ascites_albumin_g_dl",
      "ascites_albumin_g_dl": 2.0,
      "portal_hypertension_physiology": true,
      "saag_g_dl": 1.5
    }
  ]
}
```

## Response fields

- `formula` (string): saag
- `formula_expression` (string): Exact expression used
- `albumin_g_dl` (number): Serum albumin used in g/dL (after conversion)
- `ascites_albumin_g_dl` (number): Ascites albumin used in g/dL (after conversion)
- `saag_g_dl` (number): Serum albumin minus ascites albumin, 1 decimal
- `portal_hypertension_physiology` (boolean): true when saag_g_dl is >= 1.1 after 1-decimal rounding
- `citation` (object): Runyon 1992 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "albumin_g_dl": 3.5,
  "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": "Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG",
    "doi": "10.7326/0003-4819-117-3-215",
    "id": "runyon-1992",
    "source": "Ann Intern Med. 1992;117(3):215-220",
    "title": "The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites"
  },
  "formula": "saag",
  "formula_expression": "saag_g_dl = albumin_g_dl - ascites_albumin_g_dl",
  "ascites_albumin_g_dl": 2.0,
  "portal_hypertension_physiology": true,
  "saag_g_dl": 1.5
}
```

## Errors

- HTTP 400 `invalid_albumin`: albumin_g_dl (1-6) or albumin_g_l (10-60) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_ascites_albumin`: ascites_albumin_g_dl (0.1-6) or ascites_albumin_g_l (1-60) is required, 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

- [Child–Pugh](https://magentlab.com/docs/child-pugh) — Compute the Child–Turcotte–Pugh cirrhosis severity score from bilirubin, albumin, INR, encephalopathy, and ascites.

## Payment

Required query parameters must be present and valid. 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 EIP-3009 (scheme exact, assetTransferMethod eip3009) with validBefore = now + accepts[0].maxTimeoutSeconds (600 seconds). That window starts when you sign and must cover wallet confirmation plus CDP verify and settle. Magent retries transient facilitator 429/5xx before answering. Do not send upto or batch-settlement payloads; magent does not offer those schemes.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON echoing accepted, payload, and extensions when present).
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. Settlement happens before the tool runs. HTTP 503 settlement_uncertain or settle_failed: retry the same PAYMENT-SIGNATURE. Mint a new 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.

- 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.
- not offered `batch-settlement`: Not offered. Payment-channel vouchers claimed later in batches. Not the same as POST {items} bulk (that is still exact).

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

- Invalid query parameters return HTTP 400 before settlement. You are not charged.
- Settlement finishes before the tool executes (paymentFlow upfront). 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.