# Levothyroxine (LT4) replacement dose Levothyroxine dose Status: LIVE Price: $0.005 USDC `GET /api/calc/levothyroxine_dose` HTML: https://magentlab.com/docs/levothyroxine-dose Markdown: https://magentlab.com/docs/levothyroxine-dose.md 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 [Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement](https://doi.org/10.1089/thy.2014.0028) Jonklaas J, Bianco AC, Bauer AJ, et al. Thyroid. 2014;24(12):1670-1751 DOI: [10.1089/thy.2014.0028](https://doi.org/10.1089/thy.2014.0028) ## Worked example ### 70 kg adult full replacement Given: `weight_kg=70` 1. daily_lt4_mcg = 70 * 1.6 = 112.0 mcg ### 50 kg adult full replacement Given: `weight_kg=50` 1. daily_lt4_mcg = 50 * 1.6 = 80.0 mcg ### 154 lb adult full replacement Given: `weight_lb=154` 1. weight_kg = Params.weight_kg: 154 lb * 0.45359237, rounded to 4 decimals 2. daily_lt4_mcg = weight_kg * 1.6, rounded to 1 decimal ## Also searched as - levothyroxine dose - LT4 replacement - thyroxine replacement dose - hypothyroidism replacement - 1.6 mcg/kg levothyroxine - ATA levothyroxine dose - T4 full replacement ## Parameters - `weight_kg` (number, optional): Weight in kilograms (1-500). Provide weight_kg or weight_lb. - `weight_lb` (number, optional): Weight in pounds (2-1100). Converted as kg = lb * 0.45359237. ## 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/levothyroxine_dose` 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": [ { "weight_kg": "70" }, { "weight_kg": "70" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/levothyroxine-dose Example 200: ```json { "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 fields - `formula` (string): levothyroxine_dose - `formula_expression` (string): Exact expression used - `weight_kg` (number): Normalized weight in kg - `daily_lt4_mcg` (number): Adult full-replacement levothyroxine (LT4) estimate in mcg/day, 1 decimal - `citation` (object): Jonklaas et al. ATA 2014 citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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 } ``` ## Errors - HTTP 400 `invalid_weight`: weight_kg (1-500) or weight_lb (2-1100) is required 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 - [Phenytoin correction](https://magentlab.com/docs/phenytoin-correction) — Estimate an albumin-adjusted total-equivalent phenytoin concentration from observed total phenytoin and albumin, with an optional renal binding-factor change. - [Glucocorticoid dose conversion](https://magentlab.com/docs/steroid-conversion) — Convert a glucocorticoid dose among hydrocortisone, prednisone, and dexamethasone using Meikle 1977 equivalent doses (20 mg : 5 mg : 0.75 mg). ## 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.