{"uid":"cap_HWuqM8Cl07fuDEiDoaGWF","slug":"magent-phenytoin-correction-calculator-sheiner-tozer-winter-tozer-2e8cd3d3","name":"Magent Phenytoin Correction Calculator (Sheiner–Tozer / Winter–Tozer)","description":"Sheiner–Tozer / Winter–Tozer albumin-adjusted total phenytoin: Ccorr = Cobs / ((0.2 or 0.1) × albumin_g_dl + 0.1). Renal factor 0.1 when renal_impairment is true. Deterministic published arithmetic with citation; not a free phenytoin level or a dose.","url":"https://api.magentlab.com/api/calc/phenytoin_correction","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":["phenytoin_mcg_ml","renal_impairment"],"properties":{"albumin_g_l":{"type":"number","description":"Serum albumin in g/L (10-60). Converted as g/dL = g/L / 10."},"albumin_g_dl":{"type":"number","description":"Serum albumin in g/dL (1-6). Provide this or albumin_g_l."},"phenytoin_mcg_ml":{"type":"number","description":"Observed total phenytoin in µg/mL (same as mg/L). Range 0.1-80."},"renal_impairment":{"type":"boolean","description":"true uses binding factor 0.1 (Liponi/Winter–Tozer end-stage renal adjustment). false uses 0.2. true or false."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"path":"/api/calc/phenytoin_correction","count":2,"items":[{"formula":"sheiner_tozer","citation":{"id":"liponi-1984","doi":"10.1212/WNL.34.3.395","title":"Renal function and therapeutic concentrations of phenytoin","source":"Neurology. 1984;34(3):395-397","authors":"Liponi DF, Winter ME, Tozer TN"},"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.","albumin_g_dl":2,"binding_factor":0.2,"phenytoin_mcg_ml":8,"renal_impairment":false,"formula_expression":"corrected_phenytoin_mcg_ml = phenytoin_mcg_ml / ((binding_factor * albumin_g_dl) + 0.1); binding_factor 0.2, or 0.1 if renal_impairment","corrected_phenytoin_mcg_ml":16},{"formula":"sheiner_tozer","citation":{"id":"liponi-1984","doi":"10.1212/WNL.34.3.395","title":"Renal function and therapeutic concentrations of phenytoin","source":"Neurology. 1984;34(3):395-397","authors":"Liponi DF, Winter ME, Tozer TN"},"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.","albumin_g_dl":2,"binding_factor":0.2,"phenytoin_mcg_ml":8,"renal_impairment":false,"formula_expression":"corrected_phenytoin_mcg_ml = phenytoin_mcg_ml / ((binding_factor * albumin_g_dl) + 0.1); binding_factor 0.2, or 0.1 if renal_impairment","corrected_phenytoin_mcg_ml":16}]}},"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_VTyHJq8GUFQ9zO3hxu7S8","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":"Calculates albumin-adjusted (corrected) total phenytoin concentration using the Sheiner–Tozer or Winter–Tozer formula, with a renal impairment adjustment factor.","exampleAgentPrompt":"My patient has an observed total phenytoin of 12 µg/mL, a serum albumin of 2.2 g/dL, and end-stage renal disease — can you calculate the albumin-corrected phenytoin level using the Winter–Tozer formula?","exampleUseCases":[{"title":"ICU hypoalbuminemia phenytoin adjustment","prompt":"My ICU patient's total phenytoin is 9 µg/mL and their albumin is 1.8 g/dL with no renal impairment — what's the corrected phenytoin concentration?"},{"title":"Dialysis patient therapeutic drug monitoring","prompt":"Can you run the Winter–Tozer phenytoin correction for a dialysis patient with an observed phenytoin of 7.5 µg/mL and albumin of 2.5 g/dL? They have end-stage renal disease so use the renal impairment factor."},{"title":"Epilepsy clinic medication review","prompt":"Our epilepsy clinic patient has a phenytoin level of 14 µg/mL and serum albumin of 3.0 g/dL with normal kidney function — calculate the Sheiner–Tozer corrected phenytoin to see if they're truly in range."}],"resultDescription":"Returns the albumin-adjusted (corrected) total phenytoin concentration in µg/mL, computed using the Sheiner–Tozer formula (renal_impairment=false: Ccorr = Cobs / (0.2 × albumin_g_dl + 0.1)) or the Winter–Tozer renal adjustment (renal_impairment=true: Ccorr = Cobs / (0.1 × albumin_g_dl + 0.1)), along with the formula citation and input echo.","failureModes":["Missing required phenytoin_mcg_ml or renal_impairment parameters returns validation error","Albumin value out of range (e.g. <1 or >6 g/dL) may return an out-of-range error","Neither albumin_g_dl nor albumin_g_l provided results in missing-input error","Non-numeric or malformed query parameter values return 400 Bad Request","Payment failure (x402) if USDC balance is insufficient"],"whenToPreferThis":"Use this endpoint when you need a deterministic, citation-backed Sheiner–Tozer / Winter–Tozer phenytoin correction calculation — specifically when a patient has hypoalbuminemia (low albumin) or end-stage renal disease affecting phenytoin protein binding. Prefer this over manual calculation to ensure formula accuracy and auditability. This does not estimate free phenytoin or dose recommendations.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:07:57.893Z","isFirstParty":false}