# NRPE NRPE Status: LIVE Price: $0.005 USDC `GET /api/calc/nrpe` HTML: https://magentlab.com/docs/nrpe Markdown: https://magentlab.com/docs/nrpe.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Compute the Rao 2021 natriuretic response prediction equation from a spot urine sample ~2 h after IV loop diuretic using caller-assigned eGFR and BSA, serum and urine creatinine, and urine sodium. ## When to use When an agent needs published Rao 2021 predicted Na and urine output and must not invent a diuretic order, CKD-EPI eGFR, or Du Bois BSA. ## When not to use - Not a medical device. Not a diuretic order and not a diagnosis of diuretic resistance. - magent does not compute eGFR or BSA. The caller supplies egfr_ml_min_1_73m2 (5-200) and bsa_m2 (0.4-3.5). The paper used CKD-EPI and Du Bois; magent does not implement race-based 2009 CKD-EPI. - The spot urine sample is caller-timed (~2 h after IV loop diuretic in Rao 2021). magent does not time collection or assay labs. 100-150 mmol is unlabeled in the paper. ## Formula ``` na_output_mmol = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25 * (urine_sodium_mmol_l / 1000); urine_output_ml = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25 ``` ## Citation [Natriuretic Equation to Predict Loop Diuretic Response in Patients With Heart Failure](https://doi.org/10.1016/j.jacc.2020.12.022) Rao VS, Ivey-Miranda JB, Cox ZL, et al. J Am Coll Cardiol. 2021;77(6):695-708 DOI: [10.1016/j.jacc.2020.12.022](https://doi.org/10.1016/j.jacc.2020.12.022) ## Worked example ### eGFR 80, BSA 1.73 m², Scr 1.0, UCr 25, UNa 90 Given: `bsa_m2=1.73, creatinine_mg_dl=1.0, egfr_ml_min_1_73m2=80, urine_creatinine_mg_dl=25, urine_sodium_mmol_l=90` 1. urine_output_ml = 80 * (1.73/1.73) * (1.0/25) * 60 * 3.25 = 624.0 2. na_output_mmol = 624.0 * (90/1000) = 56.16 → 56.2 at 1 decimal 3. 50 ≤ 56.2 < 100 → poor_response false, suboptimal_response true, excellent_response false ## Also searched as - natriuretic response prediction equation - Rao natriuretic equation - loop diuretic sodium output - predicted natriuretic response - Testani natriuretic equation - spot urine after loop diuretic - natriuretic equation heart failure ## Parameters - `egfr_ml_min_1_73m2` (number, required): Caller-assigned eGFR in mL/min/1.73m² (5-200). magent does not compute CKD-EPI (including race-based 2009 CKD-EPI). - `bsa_m2` (number, required): Caller-assigned body surface area in m² (0.4-3.5). Paper used Du Bois. magent does not compute BSA. - `creatinine_mg_dl` (number, optional): Serum creatinine in mg/dL (0.1-20). Provide this or creatinine_umol_l, not both. - `creatinine_umol_l` (number, optional): Serum creatinine in µmol/L (9-1768). Converted as mg/dL = µmol/L / 88.42. Provide this or creatinine_mg_dl, not both. - `urine_creatinine_mg_dl` (number, optional): Urine creatinine in mg/dL (1-500). Provide this or urine_creatinine_umol_l, not both. - `urine_creatinine_umol_l` (number, optional): Urine creatinine in µmol/L (88-44210). Converted as mg/dL = µmol/L / 88.42. Provide this or urine_creatinine_mg_dl, not both. - `urine_sodium_mmol_l` (number, required): Spot urine sodium in mmol/L (1-300), ~2 h after IV loop diuretic. ## 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/nrpe` 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": [ { "bsa_m2": "1.73", "creatinine_mg_dl": "1.0", "egfr_ml_min_1_73m2": "80", "urine_creatinine_mg_dl": "25", "urine_sodium_mmol_l": "90" }, { "bsa_m2": "1.73", "creatinine_mg_dl": "1.0", "egfr_ml_min_1_73m2": "80", "urine_creatinine_mg_dl": "25", "urine_sodium_mmol_l": "90" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/nrpe Example 200: ```json { "count": 2, "path": "/api/calc/nrpe", "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": "Rao VS, Ivey-Miranda JB, Cox ZL, et al.", "doi": "10.1016/j.jacc.2020.12.022", "id": "rao-2021", "pmid": "33573739", "source": "J Am Coll Cardiol. 2021;77(6):695-708", "title": "Natriuretic Equation to Predict Loop Diuretic Response in Patients With Heart Failure" }, "formula": "nrpe", "formula_expression": "na_output_mmol = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25 * (urine_sodium_mmol_l / 1000); urine_output_ml = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25", "creatinine_mg_dl": 1.0, "bsa_m2": 1.73, "egfr_ml_min_1_73m2": 80.0, "urine_creatinine_mg_dl": 25.0, "urine_sodium_mmol_l": 90.0, "excellent_response": false, "na_output_mmol": 56.2, "poor_response": false, "suboptimal_response": true, "urine_output_ml": 624.0 }, { "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": "Rao VS, Ivey-Miranda JB, Cox ZL, et al.", "doi": "10.1016/j.jacc.2020.12.022", "id": "rao-2021", "pmid": "33573739", "source": "J Am Coll Cardiol. 2021;77(6):695-708", "title": "Natriuretic Equation to Predict Loop Diuretic Response in Patients With Heart Failure" }, "formula": "nrpe", "formula_expression": "na_output_mmol = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25 * (urine_sodium_mmol_l / 1000); urine_output_ml = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25", "creatinine_mg_dl": 1.0, "bsa_m2": 1.73, "egfr_ml_min_1_73m2": 80.0, "urine_creatinine_mg_dl": 25.0, "urine_sodium_mmol_l": 90.0, "excellent_response": false, "na_output_mmol": 56.2, "poor_response": false, "suboptimal_response": true, "urine_output_ml": 624.0 } ] } ``` ## Response fields - `formula` (string): nrpe - `formula_expression` (string): Exact Rao 2021 spot-urine natriuretic and urine-output expressions - `egfr_ml_min_1_73m2` (number): Caller-assigned eGFR in mL/min/1.73m² - `bsa_m2` (number): Caller-assigned BSA in m² - `creatinine_mg_dl` (number): Normalized serum creatinine in mg/dL - `urine_creatinine_mg_dl` (number): Normalized urine creatinine in mg/dL - `urine_sodium_mmol_l` (number): Urine sodium in mmol/L - `na_output_mmol` (number): Predicted Na output in mmol, 1 decimal (Rao 2021) - `urine_output_ml` (number): Predicted urine output in mL, 1 decimal (Rao 2021) - `poor_response` (boolean): true iff rounded na_output_mmol < 50 (Rao 2021 Methods) - `suboptimal_response` (boolean): true iff rounded na_output_mmol < 100 (Rao 2021 Methods; includes poor_response) - `excellent_response` (boolean): true iff rounded na_output_mmol > 150 (Rao 2021 Methods) - `citation` (object): Rao J Am Coll Cardiol 2021 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": "Rao VS, Ivey-Miranda JB, Cox ZL, et al.", "doi": "10.1016/j.jacc.2020.12.022", "id": "rao-2021", "pmid": "33573739", "source": "J Am Coll Cardiol. 2021;77(6):695-708", "title": "Natriuretic Equation to Predict Loop Diuretic Response in Patients With Heart Failure" }, "formula": "nrpe", "formula_expression": "na_output_mmol = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25 * (urine_sodium_mmol_l / 1000); urine_output_ml = egfr_ml_min_1_73m2 * (bsa_m2 / 1.73) * (creatinine_mg_dl / urine_creatinine_mg_dl) * 60 * 3.25", "creatinine_mg_dl": 1.0, "bsa_m2": 1.73, "egfr_ml_min_1_73m2": 80.0, "urine_creatinine_mg_dl": 25.0, "urine_sodium_mmol_l": 90.0, "excellent_response": false, "na_output_mmol": 56.2, "poor_response": false, "suboptimal_response": true, "urine_output_ml": 624.0 } ``` ## Errors - HTTP 400 `invalid_egfr`: egfr_ml_min_1_73m2 must be a number from 5 to 200 (caller-assigned eGFR; magent does not compute CKD-EPI). Returned before settlement; you are not charged. - HTTP 400 `invalid_bsa`: bsa_m2 must be a number from 0.4 to 3.5 (caller-assigned Du Bois BSA). Returned before settlement; you are not charged. - HTTP 400 `invalid_creatinine`: creatinine_mg_dl (0.1-20) or creatinine_umol_l (9-1768) is required Returned before settlement; you are not charged. - HTTP 400 `invalid_urine_creatinine`: urine_creatinine_mg_dl (1-500) or urine_creatinine_umol_l (88-44210) is required. Returned before settlement; you are not charged. - HTTP 400 `invalid_urine_sodium`: urine_sodium_mmol_l must be a number from 1 to 300. 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 - [CKD-EPI 2021 eGFR](https://magentlab.com/docs/egfr) — Compute race-free CKD-EPI 2021 creatinine eGFR in mL/min/1.73m2. - [FENa](https://magentlab.com/docs/fena) — Compute fractional excretion of sodium from plasma and urine sodium and creatinine using Espinel 1976. - [Mosteller BSA](https://magentlab.com/docs/bsa) — Compute Mosteller body surface area in m^2 from height and weight. ## 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.