# APRI (AST to platelet ratio index) APRI Status: LIVE Price: $0.005 USDC `GET /api/calc/apri` HTML: https://magentlab.com/docs/apri Markdown: https://magentlab.com/docs/apri.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Compute the AST to platelet ratio index (APRI) from AST, laboratory AST ULN, and platelet count. ## When to use When an agent needs Wai 2003 APRI arithmetic and must not invent FIB-4, a NAFLD fibrosis score, or an AST ULN of 40. ## When not to use - Not a diagnosis. Wai 2003 cut-offs are published training-set ROC coordinates, not a biopsy. - This is not FIB-4 and not the NAFLD fibrosis score. - Derived in chronic hepatitis C; magent does not re-derive cut-offs for other diseases. - ast_uln_u_l is required caller input; magent does not assume an AST ULN of 40 U/L. ## Formula ``` APRI = ((AST / AST_ULN) / platelet_count_10e9_L) * 100 ``` ## Citation [A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C](https://doi.org/10.1053/jhep.2003.50346) Wai CT, Greenson JK, Fontana RJ, et al. Hepatology. 2003;38(2):518-526 DOI: [10.1053/jhep.2003.50346](https://doi.org/10.1053/jhep.2003.50346) ## Worked example ### Wai 2003 paper example (AST 90, ULN 45, platelets 120) Given: `ast_u_l=90, ast_uln_u_l=45, platelets_10e9_l=120` 1. APRI = ((90 / 45) / 120) × 100 = (2 / 120) × 100 = 1.666… 2. Round to 2 decimals → 1.67 3. Significant fibrosis (Ishak >=3): 1.67 > 1.50 → high 4. Cirrhosis: 1.67 is not <=1.00 and not >2.00 → indeterminate ## Also searched as - AST to platelet ratio index - AST/platelet ratio - Wai APRI - aspartate aminotransferase platelet ratio - APRI score - APRI hepatitis C ## Parameters - `ast_u_l` (number, required): Aspartate aminotransferase in U/L (1-10000). - `ast_uln_u_l` (number, required): Laboratory AST upper limit of normal in U/L (5-200). Required; magent does not assume 40. - `platelets_10e9_l` (number, required): Platelet count in 10^9/L (1-2000). ## Bulk (POST) POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement. Method: `POST /api/calc/apri` Max items: 25 Price: unit_amount * n (unit 5000 atomic) Status: PREVIEW - 1 to 25 items. Each item uses the same keys as the GET query parameters. - 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": [ { "ast_u_l": "90", "ast_uln_u_l": "45", "platelets_10e9_l": "120" }, { "ast_u_l": "90", "ast_uln_u_l": "45", "platelets_10e9_l": "120" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/apri Example 200: ```json { "count": 2, "path": "/api/calc/apri", "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": "Wai CT, Greenson JK, Fontana RJ, et al.", "doi": "10.1053/jhep.2003.50346", "id": "wai-2003", "source": "Hepatology. 2003;38(2):518-526", "title": "A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C" }, "formula": "apri", "formula_expression": "APRI = ((AST / AST_ULN) / platelet_count_10e9_L) * 100", "apri": 1.67, "ast_u_l": 90.0, "ast_uln_u_l": 45.0, "platelets_10e9_l": 120.0, "wai_cirrhosis_band": "indeterminate", "wai_fibrosis_band": "high" }, { "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": "Wai CT, Greenson JK, Fontana RJ, et al.", "doi": "10.1053/jhep.2003.50346", "id": "wai-2003", "source": "Hepatology. 2003;38(2):518-526", "title": "A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C" }, "formula": "apri", "formula_expression": "APRI = ((AST / AST_ULN) / platelet_count_10e9_L) * 100", "apri": 1.67, "ast_u_l": 90.0, "ast_uln_u_l": 45.0, "platelets_10e9_l": 120.0, "wai_cirrhosis_band": "indeterminate", "wai_fibrosis_band": "high" } ] } ``` ## Response fields - `formula` (string): apri - `formula_expression` (string): Exact expression used - `ast_u_l` (number): AST in U/L - `ast_uln_u_l` (number): Laboratory AST upper limit of normal in U/L - `platelets_10e9_l` (number): Platelets in 10^9/L - `apri` (number): APRI, 2 decimal places - `wai_fibrosis_band` (string): Wai 2003 significant fibrosis (Ishak >=3) cut-offs: low (<=0.50), indeterminate, high (>1.50). Not a diagnosis. - `wai_cirrhosis_band` (string): Wai 2003 cirrhosis cut-offs: low (<=1.00), indeterminate, high (>2.00). Not a diagnosis. - `citation` (object): Hepatology 2003 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": "Wai CT, Greenson JK, Fontana RJ, et al.", "doi": "10.1053/jhep.2003.50346", "id": "wai-2003", "source": "Hepatology. 2003;38(2):518-526", "title": "A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C" }, "formula": "apri", "formula_expression": "APRI = ((AST / AST_ULN) / platelet_count_10e9_L) * 100", "apri": 1.67, "ast_u_l": 90.0, "ast_uln_u_l": 45.0, "platelets_10e9_l": 120.0, "wai_cirrhosis_band": "indeterminate", "wai_fibrosis_band": "high" } ``` ## Errors - HTTP 400 `invalid_ast`: ast_u_l must be a number from 1 to 10000 Returned before settlement; you are not charged. - HTTP 400 `invalid_ast_uln`: ast_uln_u_l must be a number from 5 to 200. Returned before settlement; you are not charged. - HTTP 400 `invalid_platelets`: platelets_10e9_l must be a number from 1 to 2000 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 - [FIB-4](https://magentlab.com/docs/fib4) — Compute the FIB-4 fibrosis index from age, AST, ALT, and platelets. ## 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 n times the GET unit. 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.