Medications · LIVE

Levothyroxine (LT4) replacement dose

Levothyroxine dose

Estimate an adult full-replacement daily levothyroxine (LT4) dose from body weight using the ATA 2014 average of approximately 1.6 μg/kg per day.

LIVE $0.005 USDC GET /api/calc/levothyroxine_dose

Markdown: /docs/levothyroxine-dose.md · Canonical: https://magentlab.com/docs/levothyroxine-dose

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

What it computes

Estimate an adult full-replacement daily levothyroxine (LT4) dose from body weight using the ATA 2014 average of approximately 1.6 μg/kg per day.

When to use

When an agent needs the published ATA adult full-replacement estimate and must not invent TSH-guided titration, a tablet strength, a pediatric dose, or pregnancy-specific dosing.

When not to use

• Not a prescription, TSH-guided titration, pediatric dose, or pregnancy-specific dose. The ATA guideline notes adjustments in pregnancy; this tool is the adult full-replacement estimate only.
• The estimate may need lean-body-mass adjustment (ATA). Elderly and cardiac patients often start lower; magent does not invent a second formula for those groups.
• magent does not choose a tablet strength. Not a medical device.

Formula

daily_lt4_mcg = weight_kg * 1.6

Citation

Title

Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement

Authors

Jonklaas J, Bianco AC, Bauer AJ, et al.

Source

Thyroid. 2014;24(12):1670-1751

DOI

10.1089/thy.2014.0028

Worked example

Also searched as

• levothyroxine dose
• LT4 replacement
• thyroxine replacement dose
• hypothyroidism replacement
• 1.6 mcg/kg levothyroxine
• ATA levothyroxine dose
• T4 full replacement

Try

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

/api/calc/levothyroxine_dose?weight_kg=70

Full URL: https://api.magentlab.com/api/calc/levothyroxine_dose?weight_kg=70

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/levothyroxine_dose?weight_kg=70"

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/levothyroxine_dose 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": [
    {
      "weight_kg": "70"
    },
    {
      "weight_kg": "70"
    }
  ]
}

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/levothyroxine_dose",
  "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": "Jonklaas J, Bianco AC, Bauer AJ, et al.",
        "doi": "10.1089/thy.2014.0028",
        "id": "jonklaas-2014",
        "pmid": "25266247",
        "source": "Thyroid. 2014;24(12):1670-1751",
        "title": "Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement"
      },
      "formula": "levothyroxine_dose",
      "formula_expression": "daily_lt4_mcg = weight_kg * 1.6",
      "weight_kg": 70.0,
      "daily_lt4_mcg": 112.0
    },
    {
      "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": "Jonklaas J, Bianco AC, Bauer AJ, et al.",
        "doi": "10.1089/thy.2014.0028",
        "id": "jonklaas-2014",
        "pmid": "25266247",
        "source": "Thyroid. 2014;24(12):1670-1751",
        "title": "Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement"
      },
      "formula": "levothyroxine_dose",
      "formula_expression": "daily_lt4_mcg = weight_kg * 1.6",
      "weight_kg": 70.0,
      "daily_lt4_mcg": 112.0
    }
  ]
}

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": "Jonklaas J, Bianco AC, Bauer AJ, et al.",
    "doi": "10.1089/thy.2014.0028",
    "id": "jonklaas-2014",
    "pmid": "25266247",
    "source": "Thyroid. 2014;24(12):1670-1751",
    "title": "Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement"
  },
  "formula": "levothyroxine_dose",
  "formula_expression": "daily_lt4_mcg = weight_kg * 1.6",
  "weight_kg": 70.0,
  "daily_lt4_mcg": 112.0
}

Client errors (HTTP 400)

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

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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.