# Martin estimated LDL-C

Martin LDL-C

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/martin_ldl`
HTML: https://magentlab.com/docs/martin-ldl
Markdown: https://magentlab.com/docs/martin-ldl.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Estimate LDL-C from total cholesterol, HDL, and triglycerides using Martin 2013: non-HDL-C minus triglycerides divided by the published 180-cell TG:VLDL-C factor (mg/dL).

## When to use

When an agent needs Martin 2013 LDL arithmetic from a standard lipid panel in mg/dL and must not apply Friedewald TG/5 or Sampson 2020.

## When not to use

- Not a medical device, not a diagnosis, and not a statin order. Direct LDL assay is out of scope.
- mg/dL only. magent does not convert mmol/L.
- Not Friedewald (fixed factor 5) and not Sampson 2020.
- Triglycerides below 7 or at 400 mg/dL or higher are rejected. The table's first TG row starts at 7; the paper's primary concordance analysis is triglycerides lower than 400 mg/dL.
- The paper notes remaining TG:VLDL-C variance unexplained by the standard lipid profile, and limited performance in severe hypertriglyceridemia and type III Fredrickson-Levy dyslipidemia.

## Formula

```
ldl_c_mg_dl = (total_cholesterol_mg_dl - hdl_mg_dl) - (triglycerides_mg_dl / factor); factor is the Martin 2013 180-cell median TG:VLDL-C ratio by non-HDL-C and TG strata (mg/dL); not Friedewald factor 5
```

## Citation

[Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol](https://doi.org/10.1001/jama.2013.280532)
Martin SS, Blaha MJ, Elshazly MB, et al.
JAMA. 2013;310(19):2061-2068
DOI: [10.1001/jama.2013.280532](https://doi.org/10.1001/jama.2013.280532)

## Worked example

### TC 200, HDL 50, TG 150 mg/dL

Given: `hdl_mg_dl=50, total_cholesterol_mg_dl=200, triglycerides_mg_dl=150`

1. non-HDL-C = 200 - 50 = 150 mg/dL (non-HDL-C stratum 130-159)
2. TG 150 mg/dL is TG stratum 147-154; Martin 2013 factor = 5.7
3. LDL-C = 150 - (150 / 5.7) = 123.7 mg/dL


## Also searched as

- Martin equation LDL
- Martin 2013 LDL-C
- adjustable factor LDL
- TG VLDL-C ratio table
- novel method vs Friedewald
- estimated LDL cholesterol Martin

## Parameters

- `total_cholesterol_mg_dl` (number, required): Total cholesterol in mg/dL (50-500). mg/dL only; magent does not convert mmol/L.
- `hdl_mg_dl` (number, required): HDL cholesterol in mg/dL (5-150). Must be less than total cholesterol so non-HDL-C is positive.
- `triglycerides_mg_dl` (number, required): Triglycerides in mg/dL (7-399). The Martin 2013 table first TG row starts at 7. Values of 400 or higher are rejected; that is the paper's primary analysis cut.

## Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/martin_ldl`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
- 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": [
    {
      "hdl_mg_dl": "50",
      "total_cholesterol_mg_dl": "200",
      "triglycerides_mg_dl": "150"
    },
    {
      "hdl_mg_dl": "50",
      "total_cholesterol_mg_dl": "200",
      "triglycerides_mg_dl": "150"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/martin-ldl

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/martin_ldl",
  "items": [
    {
      "factor": 5.7,
      "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": "Martin SS, Blaha MJ, Elshazly MB, et al.",
        "doi": "10.1001/jama.2013.280532",
        "id": "martin-2013",
        "pmid": "24240933",
        "source": "JAMA. 2013;310(19):2061-2068",
        "title": "Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol"
      },
      "formula": "martin",
      "formula_expression": "ldl_c_mg_dl = (total_cholesterol_mg_dl - hdl_mg_dl) - (triglycerides_mg_dl / factor); factor is the Martin 2013 180-cell median TG:VLDL-C ratio by non-HDL-C and TG strata (mg/dL); not Friedewald factor 5",
      "hdl_mg_dl": 50.0,
      "triglycerides_mg_dl": 150.0,
      "total_cholesterol_mg_dl": 200.0,
      "ldl_c_mg_dl": 123.7,
      "non_hdl_c_mg_dl": 150.0
    },
    {
      "factor": 5.7,
      "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": "Martin SS, Blaha MJ, Elshazly MB, et al.",
        "doi": "10.1001/jama.2013.280532",
        "id": "martin-2013",
        "pmid": "24240933",
        "source": "JAMA. 2013;310(19):2061-2068",
        "title": "Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol"
      },
      "formula": "martin",
      "formula_expression": "ldl_c_mg_dl = (total_cholesterol_mg_dl - hdl_mg_dl) - (triglycerides_mg_dl / factor); factor is the Martin 2013 180-cell median TG:VLDL-C ratio by non-HDL-C and TG strata (mg/dL); not Friedewald factor 5",
      "hdl_mg_dl": 50.0,
      "triglycerides_mg_dl": 150.0,
      "total_cholesterol_mg_dl": 200.0,
      "ldl_c_mg_dl": 123.7,
      "non_hdl_c_mg_dl": 150.0
    }
  ]
}
```

## Response fields

- `formula` (string): martin
- `formula_expression` (string): Martin 2013 expression with table factor
- `total_cholesterol_mg_dl` (number): Input total cholesterol in mg/dL
- `hdl_mg_dl` (number): Input HDL cholesterol in mg/dL
- `triglycerides_mg_dl` (number): Input triglycerides in mg/dL
- `non_hdl_c_mg_dl` (number): Total cholesterol minus HDL, 1 decimal
- `factor` (number): Martin 2013 180-cell TG:VLDL-C median for the specimen's strata
- `ldl_c_mg_dl` (number): Estimated LDL-C in mg/dL, 1 decimal
- `citation` (object): Martin JAMA 2013 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "factor": 5.7,
  "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": "Martin SS, Blaha MJ, Elshazly MB, et al.",
    "doi": "10.1001/jama.2013.280532",
    "id": "martin-2013",
    "pmid": "24240933",
    "source": "JAMA. 2013;310(19):2061-2068",
    "title": "Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol"
  },
  "formula": "martin",
  "formula_expression": "ldl_c_mg_dl = (total_cholesterol_mg_dl - hdl_mg_dl) - (triglycerides_mg_dl / factor); factor is the Martin 2013 180-cell median TG:VLDL-C ratio by non-HDL-C and TG strata (mg/dL); not Friedewald factor 5",
  "hdl_mg_dl": 50.0,
  "triglycerides_mg_dl": 150.0,
  "total_cholesterol_mg_dl": 200.0,
  "ldl_c_mg_dl": 123.7,
  "non_hdl_c_mg_dl": 150.0
}
```

## Errors

- HTTP 400 `invalid_martin_ldl`: Martin LDL-C needs total cholesterol, HDL, and triglycerides in published mg/dL ranges (Martin 2013). 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

- [Friedewald LDL-C](https://magentlab.com/docs/friedewald) — Estimate LDL-C from total cholesterol, HDL, and triglycerides using Friedewald 1972.
- [Sampson LDL-C](https://magentlab.com/docs/sampson) — Estimate LDL-C from total cholesterol, HDL, and triglycerides using Sampson 2020.

## Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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 accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact 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.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- 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.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. 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

- HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
- exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. 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.