# Mentzer Index Calculator

> Mentzer Index Calculator is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Computes the Mentzer index (MCV ÷ RBC count) to help differentiate β-thalassemia trait from iron deficiency anemia using the original 1973 Lancet criteria.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/mentzer
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mentzer-index-calculator-743c3642
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mE0NRKdZnTKlXzQaAFf7W

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability mentzer-index-calculator-743c3642
```

Example prompt: 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?

## When to prefer this

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.

## Known failure modes

- 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

## How this service works

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.

## Output

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.

## Request schema (JSON Schema)

```json
{
 "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"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "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"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mentzer-index-calculator-743c3642/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)