Electrolytes / glucose · LIVE

Urine anion gap

Compute the urine anion gap from urine sodium, potassium, and chloride as a surrogate for ammonium excretion in hyperchloremic metabolic acidosis.

LIVE $0.005 USDC GET /api/calc/urine_anion_gap

Markdown: /docs/urine-anion-gap.md · Canonical: https://magentlab.com/docs/urine-anion-gap

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

What it computes

Compute the urine anion gap from urine sodium, potassium, and chloride as a surrogate for ammonium excretion in hyperchloremic metabolic acidosis.

When to use

When an agent needs the Batlle 1988 urine anion gap and must not invent an RTA or diarrhea diagnosis from the sign of the gap.

When not to use

• Not a diagnosis. Negative versus positive is a Batlle 1988 interpretive band for NH4+ excretion, not a diagnosis of RTA or GI bicarbonate loss.
• Does not measure urine ammonium. mEq/L equals mmol/L for these monovalent ions.
• Does not interpret urine pH or net acid excretion beyond the Na + K − Cl gap.

Formula

urine_anion_gap_mmol_l = urine_sodium_mmol_l + urine_potassium_mmol_l - urine_chloride_mmol_l

Citation

Title

The use of the urinary anion gap in the diagnosis of hyperchloremic metabolic acidosis

Authors

Batlle DC, Hizon M, Cohen E, Gutterman C, Gupta R

Source

N Engl J Med. 1988;318(10):594-599

DOI

10.1056/NEJM198803033180902

Worked example

Also searched as

• urine anion gap
• urinary anion gap
• UAG
• urine net charge
• Batlle urinary anion gap
• urinary NH4 surrogate

Try

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

/api/calc/urine_anion_gap?urine_sodium_mmol_l=20&urine_potassium_mmol_l=30&urine_chloride_mmol_l=90

Full URL: https://api.magentlab.com/api/calc/urine_anion_gap?urine_sodium_mmol_l=20&urine_potassium_mmol_l=30&urine_chloride_mmol_l=90

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/urine_anion_gap?urine_sodium_mmol_l=20&urine_potassium_mmol_l=30&urine_chloride_mmol_l=90"

Parameters

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/urine_anion_gap 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": [
    {
      "urine_chloride_mmol_l": "90",
      "urine_potassium_mmol_l": "30",
      "urine_sodium_mmol_l": "20"
    },
    {
      "urine_chloride_mmol_l": "90",
      "urine_potassium_mmol_l": "30",
      "urine_sodium_mmol_l": "20"
    }
  ]
}

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/urine_anion_gap",
  "items": [
    {
      "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": "Batlle DC, Hizon M, Cohen E, Gutterman C, Gupta R",
        "doi": "10.1056/NEJM198803033180902",
        "id": "batlle-1988",
        "source": "N Engl J Med. 1988;318(10):594-599",
        "title": "The use of the urinary anion gap in the diagnosis of hyperchloremic metabolic acidosis"
      },
      "formula": "urine_anion_gap",
      "formula_expression": "urine_anion_gap_mmol_l = urine_sodium_mmol_l + urine_potassium_mmol_l - urine_chloride_mmol_l",
      "urine_sodium_mmol_l": 20.0,
      "uag_band": "negative",
      "urine_anion_gap_mmol_l": -40.0,
      "urine_chloride_mmol_l": 90.0,
      "urine_potassium_mmol_l": 30.0
    },
    {
      "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": "Batlle DC, Hizon M, Cohen E, Gutterman C, Gupta R",
        "doi": "10.1056/NEJM198803033180902",
        "id": "batlle-1988",
        "source": "N Engl J Med. 1988;318(10):594-599",
        "title": "The use of the urinary anion gap in the diagnosis of hyperchloremic metabolic acidosis"
      },
      "formula": "urine_anion_gap",
      "formula_expression": "urine_anion_gap_mmol_l = urine_sodium_mmol_l + urine_potassium_mmol_l - urine_chloride_mmol_l",
      "urine_sodium_mmol_l": 20.0,
      "uag_band": "negative",
      "urine_anion_gap_mmol_l": -40.0,
      "urine_chloride_mmol_l": 90.0,
      "urine_potassium_mmol_l": 30.0
    }
  ]
}

Response

Example JSON

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

{
  "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": "Batlle DC, Hizon M, Cohen E, Gutterman C, Gupta R",
    "doi": "10.1056/NEJM198803033180902",
    "id": "batlle-1988",
    "source": "N Engl J Med. 1988;318(10):594-599",
    "title": "The use of the urinary anion gap in the diagnosis of hyperchloremic metabolic acidosis"
  },
  "formula": "urine_anion_gap",
  "formula_expression": "urine_anion_gap_mmol_l = urine_sodium_mmol_l + urine_potassium_mmol_l - urine_chloride_mmol_l",
  "urine_sodium_mmol_l": 20.0,
  "uag_band": "negative",
  "urine_anion_gap_mmol_l": -40.0,
  "urine_chloride_mmol_l": 90.0,
  "urine_potassium_mmol_l": 30.0
}

Client errors (HTTP 400)

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

Related tools

• Anion gap — Compute the serum anion gap from sodium, chloride, and bicarbonate, with or without potassium, using the Emmett–Narins 1977 formulas. formula is required.
• Stool osmotic gap — Compute the Eherer–Fordtran fecal osmotic gap from stool sodium and potassium, using measured stool osmolality when supplied or 290 mOsm/kg when omitted.

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.
• 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.