{"uid":"cap_mE0NRKdZnTKlXzQaAFf7W","slug":"mentzer-index-calculator-743c3642","name":"Mentzer Index Calculator","description":"Mentzer index as MCV in fL divided by RBC count in millions per µL (Mentzer 1973 Lancet letter). Quotient <13 favors β-thalassaemia trait; >13 favors iron deficiency; 13 is indeterminate. Deterministic published arithmetic with citation. Not a diagnosis of thalassemia or iron deficiency; magent does not apply later cutoffs that are not in that letter.","url":"https://api.magentlab.com/api/calc/mentzer","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":["mcv_fl","rbc_million_ul"],"properties":{"mcv_fl":{"type":"number","description":"Mean corpuscular volume in fL (50-120)."},"rbc_million_ul":{"type":"number","description":"Red-cell count in millions per µL (1.0-8.0). Required."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"path":"/api/calc/mentzer","count":2,"items":[{"mcv_fl":70,"formula":"mentzer","citation":{"id":"mentzer-1973","doi":"10.1016/s0140-6736(73)91446-3","pmid":"4123424","title":"Differentiation of iron deficiency from thalassaemia trait","source":"Lancet. 1973 Apr 21;1(7808):882","authors":"Mentzer WC Jr"},"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.","mentzer_band":"thalassemia_trait","mentzer_index":12.5,"rbc_million_ul":5.6,"formula_expression":"mentzer_index = mcv_fl / rbc_million_ul"},{"mcv_fl":70,"formula":"mentzer","citation":{"id":"mentzer-1973","doi":"10.1016/s0140-6736(73)91446-3","pmid":"4123424","title":"Differentiation of iron deficiency from thalassaemia trait","source":"Lancet. 1973 Apr 21;1(7808):882","authors":"Mentzer WC Jr"},"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.","mentzer_band":"thalassemia_trait","mentzer_index":12.5,"rbc_million_ul":5.6,"formula_expression":"mentzer_index = mcv_fl / rbc_million_ul"}]}},"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_BHoWKvxk4nFBm4KFRM0Hs","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 Mentzer index (MCV ÷ RBC count) to help differentiate β-thalassemia trait from iron deficiency anemia using the original 1973 Lancet criteria.","exampleAgentPrompt":"My patient has a MCV of 68 fL and an RBC count of 5.8 million per µL — can you calculate the Mentzer index and tell me whether it favors beta-thalassemia trait or iron deficiency?","exampleUseCases":[{"title":"Microcytic anemia triage in clinic","prompt":"I've got a patient with MCV 72 fL and RBC 5.5 million per µL — run the Mentzer index and tell me if this leans toward thalassemia trait or iron deficiency based on the 1973 Lancet cutoffs."},{"title":"Automated CBC interpretation in EHR workflow","prompt":"For the CBC that just came in — MCV is 64 fL and RBC is 6.1 million per µL — compute the Mentzer index so I can include it in the hematology note."},{"title":"Pediatric anemia workup screening","prompt":"My pediatric patient has MCV 75 fL and RBC count of 4.2 million per µL. What does the Mentzer index say — does this favor thalassemia trait or iron deficiency?"}],"resultDescription":"Returns the computed Mentzer index (MCV in fL divided by RBC in millions per µL) along with the 1973 Lancet-based interpretation: values below 13 favor β-thalassemia trait, above 13 favor iron deficiency anemia, and 13 is indeterminate. This is a deterministic arithmetic result, not a clinical diagnosis.","failureModes":["MCV out of range (50–120 fL) returns validation error","RBC out of range (1.0–8.0 million/µL) returns validation error","Missing required query parameters mcv_fl or rbc_million_ul returns 400 error","Division by zero if RBC is zero (rejected by range constraint)","Payment not included or insufficient USDC returns 402"],"whenToPreferThis":"Use this endpoint when you need a fast, deterministic, citation-anchored Mentzer index calculation using exactly the original 1973 Lancet formula — no modified cutoffs, no later revisions. Ideal for embedding in automated CBC interpretation pipelines, EHR notes, or hematology consult workflows where auditability and adherence to the original published arithmetic matter.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T00:44:43.031Z","isFirstParty":false}