{"uid":"cap_9-f69ICGYE7MBkSbSUKz5","slug":"4ts-score-calculator-for-heparin-induced-thrombocytopenia-hit-b4d0b8f9","name":"4Ts Score Calculator for Heparin-Induced Thrombocytopenia (HIT)","description":"4Ts score (Lo 2006) for heparin-induced thrombocytopenia pretest probability. Four caller-assigned integers 0-2 (thrombocytopenia, timing, thrombosis, other causes) using the published table; magent sums only (max 8). Bands 0-3 low, 4-5 intermediate, and 6-8 high pretest probability. Not a diagnosis of HIT, not the HEP score, and not an antibody result. magent does not grade platelet counts or day of onset.","url":"https://api.magentlab.com/api/calc/four_ts","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"headers":{"type":"object","additionalProperties":{"type":"string"}},"queryParams":{"type":"object","required":["thrombocytopenia","timing","thrombosis","other_causes"],"properties":{"timing":{"type":"integer","description":"Caller-assigned Lo 2006 timing points (0, 1, or 2). magent does not infer day of onset. 2: clear onset days 5-10, or <=1 day with prior heparin within 30 days. 1: consistent with days 5-10 but not clear; onset after day 10; or <=1 day with heparin 30-100 days ago. 0: fall too early without recent heparin."},"thrombosis":{"type":"integer","description":"Caller-assigned Lo 2006 thrombosis points (0, 1, or 2). 2: new thrombosis, skin necrosis, or acute systemic reaction after heparin bolus. 1: progressive/recurrent thrombosis, silent thrombosis, or erythematous skin lesions. 0: none."},"other_causes":{"type":"integer","description":"Caller-assigned Lo 2006 other (oTher) causes of thrombocytopenia (0, 1, or 2). More points = more HIT-like. 2: no other apparent cause. 1: possible other cause. 0: definite other cause."},"thrombocytopenia":{"type":"integer","description":"Caller-assigned Lo 2006 thrombocytopenia points (0, 1, or 2). magent does not grade platelet counts. 2: platelet fall >50% AND nadir >=20. 1: fall 30-50% OR nadir 10-19. 0: fall <30% OR nadir <10."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"path":"/api/calc/four_ts","count":2,"items":[{"score":0,"formula":"four_ts","citation":{"id":"lo-2006","doi":"10.1111/j.1538-7836.2006.01787.x","title":"Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings","source":"J Thromb Haemost. 2006;4(4):759-765","authors":"Lo GK, Juhl D, Warkentin TE, Sigouin CS, Eichler P, Greinacher A"},"max_score":8,"components":[{"value":0,"factor":"thrombocytopenia","points":0,"present":false},{"value":0,"factor":"timing","points":0,"present":false},{"value":0,"factor":"thrombosis","points":0,"present":false},{"value":0,"factor":"other_causes","points":0,"present":false}],"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.","four_ts_band":"0-3","formula_expression":"4Ts = thrombocytopenia + timing + thrombosis + other_causes; each 0-2 caller-assigned from Lo 2006 table; pretest probability low 0-3, intermediate 4-5, high 6-8; max 8"},{"score":0,"formula":"four_ts","citation":{"id":"lo-2006","doi":"10.1111/j.1538-7836.2006.01787.x","title":"Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings","source":"J Thromb Haemost. 2006;4(4):759-765","authors":"Lo GK, Juhl D, Warkentin TE, Sigouin CS, Eichler P, Greinacher A"},"max_score":8,"components":[{"value":0,"factor":"thrombocytopenia","points":0,"present":false},{"value":0,"factor":"timing","points":0,"present":false},{"value":0,"factor":"thrombosis","points":0,"present":false},{"value":0,"factor":"other_causes","points":0,"present":false}],"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.","four_ts_band":"0-3","formula_expression":"4Ts = thrombocytopenia + timing + thrombosis + other_causes; each 0-2 caller-assigned from Lo 2006 table; pretest probability low 0-3, intermediate 4-5, high 6-8; max 8"}]}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_kK4oYussPVpU5Z7GKTnbV","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the Lo 2006 4Ts pretest probability score for heparin-induced thrombocytopenia (HIT), returning a sum (0–8) and risk band (low/intermediate/high).","exampleAgentPrompt":"Calculate the 4Ts HIT score for a patient where I'm assigning 2 points for thrombocytopenia, 1 point for timing, 2 points for thrombosis, and 1 point for other causes — what's the total and risk band?","exampleUseCases":[{"title":"HIT workup triage in the ICU","prompt":"My ICU patient developed a 55% platelet drop on day 6 of heparin and has a new DVT — I'm assigning 2 for thrombocytopenia, 2 for timing, 2 for thrombosis, and 2 for other causes (no obvious alternative). Calculate the 4Ts score and tell me the risk band."},{"title":"Low-risk reassurance before continuing heparin","prompt":"My patient's platelet fell 20% on day 2 of heparin with no thrombosis and a clear alternative cause. I'm scoring 0 for thrombocytopenia, 0 for timing, 0 for thrombosis, and 0 for other causes — run the 4Ts calculation and confirm whether this is low probability for HIT."},{"title":"Intermediate probability guiding antibody testing decision","prompt":"I have a patient with a 35% platelet decline, timing consistent with days 5–10 but not clear, erythematous skin lesions at the heparin site, and a possible alternative cause — that's 1 for thrombocytopenia, 1 for timing, 1 for thrombosis, and 1 for other causes. What's the 4Ts total and pretest probability band?"}],"resultDescription":"Returns the integer sum of the four caller-assigned 4Ts components (range 0–8) and a risk classification band: 0–3 = low pretest probability, 4–5 = intermediate, 6–8 = high. Does not return a diagnosis, antibody result, or HEP score.","failureModes":["Any of the four integer parameters (thrombocytopenia, timing, thrombosis, other_causes) missing → validation error","Values outside the 0–2 integer range for any parameter → likely rejection or unexpected behavior","Non-integer (float or string) inputs for score fields → schema validation failure","Caller incorrectly pre-grades platelet counts or timing — magent does not sanity-check clinical assignments, so miscoded inputs yield a valid but clinically wrong score"],"whenToPreferThis":"Use this endpoint when you need a fast, deterministic Lo 2006 4Ts score sum and risk band without building the arithmetic yourself. Prefer it over a generic LLM calculation when you need reproducible, auditable clinical scoring. It is not the HEP score and not an antibody assay interpreter — use a different tool for those. Best suited for clinical decision support pipelines where the calling agent or clinician has already assigned the four Lo 2006 point values.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:15:00.152Z","isFirstParty":false}