# Light's criteria (pleural fluid) Light's criteria ## Also searched as - Light's criteria - Light criteria pleural - transudate vs exudate - pleural fluid LDH - pleural protein ratio - Light 1972 effusion Status: LIVE Price: $0.005 USDC `GET /api/calc/lights` HTML: https://magentlab.com/docs/lights Markdown: https://magentlab.com/docs/lights.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Apply Light 1972 pleural fluid criteria from protein ratio, LDH ratio, and pleural LDH versus two-thirds the laboratory LDH upper limit of normal. ## When to use When an agent needs Light 1972 transudate versus exudate arithmetic and must not invent Heffner abbreviated criteria, an NT-proBNP rule, or a cause of the effusion. ## When not to use - Not a diagnosis of the cause of an effusion (for example CHF versus infection). - Not Heffner's abbreviated two-test criteria and not an NT-proBNP rule. - magent does not interpret a chest x-ray. - ldh_uln_u_l is required; magent does not assume a laboratory ULN of 200 U/L. - Cutoffs are strictly greater than 0.5, 0.6, and two-thirds ULN (equality is not exudate by that criterion). ## Formula ``` exudate if pleural_protein_g_dl / serum_protein_g_dl > 0.5 or pleural_ldh_u_l / serum_ldh_u_l > 0.6 or pleural_ldh_u_l > (2/3) * ldh_uln_u_l ``` ## Citation [Pleural effusions: the diagnostic separation of transudates and exudates](https://doi.org/10.7326/0003-4819-77-4-507) Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr Ann Intern Med. 1972;77(4):507-513 DOI: [10.7326/0003-4819-77-4-507](https://doi.org/10.7326/0003-4819-77-4-507) ## Worked example ### Protein 3.0/6.0, LDH 100/200, ULN 200 — transudate Given: `ldh_uln_u_l=200, pleural_ldh_u_l=100, pleural_protein_g_dl=3.0, serum_ldh_u_l=200, serum_protein_g_dl=6.0` 1. protein_ratio = 3.0 / 6.0 = 0.5 (not > 0.5) 2. ldh_ratio = 100 / 200 = 0.5 (not > 0.6) 3. ldh_two_thirds_uln = (2/3) × 200 = 133.3; pleural LDH 100 is not > 133.3 4. no criterion met → transudate ### Protein 4.0/6.0 — exudate by protein ratio Given: `ldh_uln_u_l=200, pleural_ldh_u_l=100, pleural_protein_g_dl=4.0, serum_ldh_u_l=200, serum_protein_g_dl=6.0` 1. protein_ratio = 4.0 / 6.0 = 0.667 (> 0.5) 2. any one criterion met → exudate ## Parameters - `pleural_protein_g_dl` (number, required): Pleural fluid protein in g/dL (0.1-20). - `serum_protein_g_dl` (number, required): Serum protein in g/dL (0.1-20). - `pleural_ldh_u_l` (number, required): Pleural fluid LDH in U/L (1-10000). - `serum_ldh_u_l` (number, required): Serum LDH in U/L (1-10000). - `ldh_uln_u_l` (number, required): Laboratory LDH upper limit of normal in U/L (50-2000). Required; magent does not assume 200. ## 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/lights` 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": [ { "ldh_uln_u_l": "200", "pleural_ldh_u_l": "100", "pleural_protein_g_dl": "3.0", "serum_ldh_u_l": "200", "serum_protein_g_dl": "6.0" }, { "ldh_uln_u_l": "200", "pleural_ldh_u_l": "100", "pleural_protein_g_dl": "3.0", "serum_ldh_u_l": "200", "serum_protein_g_dl": "6.0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/lights Example 200: ```json { "count": 2, "path": "/api/calc/lights", "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": "Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr", "doi": "10.7326/0003-4819-77-4-507", "id": "light-1972", "source": "Ann Intern Med. 1972;77(4):507-513", "title": "Pleural effusions: the diagnostic separation of transudates and exudates" }, "formula": "lights", "formula_expression": "exudate if pleural_protein_g_dl / serum_protein_g_dl > 0.5 or pleural_ldh_u_l / serum_ldh_u_l > 0.6 or pleural_ldh_u_l > (2/3) * ldh_uln_u_l", "criteria": [ { "value": 0.5, "factor": "protein_ratio_gt_0_5", "met": false }, { "value": 0.5, "factor": "ldh_ratio_gt_0_6", "met": false }, { "value": 100.0, "factor": "pleural_ldh_gt_two_thirds_uln", "met": false } ], "exudate": false, "ldh_ratio": 0.5, "ldh_two_thirds_uln": 133.3, "pleural_ldh_u_l": 100.0, "protein_ratio": 0.5 }, { "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": "Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr", "doi": "10.7326/0003-4819-77-4-507", "id": "light-1972", "source": "Ann Intern Med. 1972;77(4):507-513", "title": "Pleural effusions: the diagnostic separation of transudates and exudates" }, "formula": "lights", "formula_expression": "exudate if pleural_protein_g_dl / serum_protein_g_dl > 0.5 or pleural_ldh_u_l / serum_ldh_u_l > 0.6 or pleural_ldh_u_l > (2/3) * ldh_uln_u_l", "criteria": [ { "value": 0.5, "factor": "protein_ratio_gt_0_5", "met": false }, { "value": 0.5, "factor": "ldh_ratio_gt_0_6", "met": false }, { "value": 100.0, "factor": "pleural_ldh_gt_two_thirds_uln", "met": false } ], "exudate": false, "ldh_ratio": 0.5, "ldh_two_thirds_uln": 133.3, "pleural_ldh_u_l": 100.0, "protein_ratio": 0.5 } ] } ``` ## Response fields - `formula` (string): lights - `formula_expression` (string): Exact expression used - `exudate` (boolean): true if any Light 1972 criterion is met (strictly greater than). Not a diagnosis of cause. - `protein_ratio` (number): pleural_protein_g_dl / serum_protein_g_dl, 3 decimals - `ldh_ratio` (number): pleural_ldh_u_l / serum_ldh_u_l, 3 decimals - `ldh_two_thirds_uln` (number): (2/3) × ldh_uln_u_l, 1 decimal - `pleural_ldh_u_l` (number): Pleural fluid LDH used, U/L - `criteria` (array): Three Light 1972 rows (protein_ratio_gt_0_5, ldh_ratio_gt_0_6, pleural_ldh_gt_two_thirds_uln), each with factor, met, and value - `citation` (object): Light et al. 1972 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": "Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr", "doi": "10.7326/0003-4819-77-4-507", "id": "light-1972", "source": "Ann Intern Med. 1972;77(4):507-513", "title": "Pleural effusions: the diagnostic separation of transudates and exudates" }, "formula": "lights", "formula_expression": "exudate if pleural_protein_g_dl / serum_protein_g_dl > 0.5 or pleural_ldh_u_l / serum_ldh_u_l > 0.6 or pleural_ldh_u_l > (2/3) * ldh_uln_u_l", "criteria": [ { "value": 0.5, "factor": "protein_ratio_gt_0_5", "met": false }, { "value": 0.5, "factor": "ldh_ratio_gt_0_6", "met": false }, { "value": 100.0, "factor": "pleural_ldh_gt_two_thirds_uln", "met": false } ], "exudate": false, "ldh_ratio": 0.5, "ldh_two_thirds_uln": 133.3, "pleural_ldh_u_l": 100.0, "protein_ratio": 0.5 } ``` ## Errors - HTTP 400 `invalid_pleural_protein`: pleural_protein_g_dl must be a number from 0.1 to 20. Returned before settlement; you are not charged. - HTTP 400 `invalid_serum_protein`: serum_protein_g_dl must be a number from 0.1 to 20. Returned before settlement; you are not charged. - HTTP 400 `invalid_pleural_ldh`: pleural_ldh_u_l must be a number from 1 to 10000. Returned before settlement; you are not charged. - HTTP 400 `invalid_serum_ldh`: serum_ldh_u_l must be a number from 1 to 10000. Returned before settlement; you are not charged. - HTTP 400 `invalid_ldh_uln`: ldh_uln_u_l must be a number from 50 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 - [A-a O2 gradient](https://magentlab.com/docs/aa-gradient) — Compute the alveolar–arterial oxygen gradient from arterial blood-gas values using the simplified ideal alveolar-gas equation. ## 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.