Lipids · LIVE

Friedewald estimated LDL-C

Friedewald LDL-C

Estimate LDL-C from total cholesterol, HDL, and triglycerides using Friedewald 1972.

LIVE $0.005 USDC GET /api/calc/friedewald

Markdown: /docs/friedewald.md · Canonical: https://magentlab.com/docs/friedewald

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

What it computes

Estimate LDL-C from total cholesterol, HDL, and triglycerides using Friedewald 1972.

When to use

When an agent needs Friedewald LDL arithmetic and must not invent a VLDL factor or mix mg/dL with mmol/L.

When not to use

• Not a diagnosis and not a statin order. Direct LDL assay is out of scope.
• Triglycerides above 400 mg/dL (or 4.5 mmol/L) are rejected. The paper's VLDL estimate of TG/5 is for typical specimens only.

Formula

ldl_c_mg_dl = total_cholesterol_mg_dl - hdl_mg_dl - (triglycerides_mg_dl / 5); ldl_c_mmol_l = total_cholesterol_mmol_l - hdl_mmol_l - (triglycerides_mmol_l / 2.2)

Citation

Title

Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge

Authors

Friedewald WT, Levy RI, Fredrickson DS

Source

Clin Chem. 1972;18(6):499-502

DOI

10.1093/clinchem/18.6.499

Worked example

Also searched as

• Friedewald equation
• LDL-C estimate
• calculated LDL cholesterol
• VLDL triglycerides/5
• Friedewald 1972
• estimated LDL-C

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/friedewald?total_cholesterol_mg_dl=200&hdl_mg_dl=50&triglycerides_mg_dl=150

Full URL: https://api.magentlab.com/api/calc/friedewald?total_cholesterol_mg_dl=200&hdl_mg_dl=50&triglycerides_mg_dl=150

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/friedewald?total_cholesterol_mg_dl=200&hdl_mg_dl=50&triglycerides_mg_dl=150"

Parameters

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.

POST /api/calc/friedewald Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 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 (fixture)

{
  "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"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/friedewald",
  "items": [
    {
      "unit": "mg_dl",
      "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": "Friedewald WT, Levy RI, Fredrickson DS",
        "doi": "10.1093/clinchem/18.6.499",
        "id": "friedewald-1972",
        "source": "Clin Chem. 1972;18(6):499-502",
        "title": "Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge"
      },
      "formula": "friedewald",
      "formula_expression": "ldl_c_mg_dl = total_cholesterol_mg_dl - hdl_mg_dl - (triglycerides_mg_dl / 5)",
      "hdl_mg_dl": 50.0,
      "total_cholesterol_mg_dl": 200.0,
      "triglycerides_mg_dl": 150.0,
      "ldl_c_mg_dl": 120.0,
      "ldl_c_mmol_l": 3.1
    },
    {
      "unit": "mg_dl",
      "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": "Friedewald WT, Levy RI, Fredrickson DS",
        "doi": "10.1093/clinchem/18.6.499",
        "id": "friedewald-1972",
        "source": "Clin Chem. 1972;18(6):499-502",
        "title": "Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge"
      },
      "formula": "friedewald",
      "formula_expression": "ldl_c_mg_dl = total_cholesterol_mg_dl - hdl_mg_dl - (triglycerides_mg_dl / 5)",
      "hdl_mg_dl": 50.0,
      "total_cholesterol_mg_dl": 200.0,
      "triglycerides_mg_dl": 150.0,
      "ldl_c_mg_dl": 120.0,
      "ldl_c_mmol_l": 3.1
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "unit": "mg_dl",
  "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": "Friedewald WT, Levy RI, Fredrickson DS",
    "doi": "10.1093/clinchem/18.6.499",
    "id": "friedewald-1972",
    "source": "Clin Chem. 1972;18(6):499-502",
    "title": "Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge"
  },
  "formula": "friedewald",
  "formula_expression": "ldl_c_mg_dl = total_cholesterol_mg_dl - hdl_mg_dl - (triglycerides_mg_dl / 5)",
  "hdl_mg_dl": 50.0,
  "total_cholesterol_mg_dl": 200.0,
  "triglycerides_mg_dl": 150.0,
  "ldl_c_mg_dl": 120.0,
  "ldl_c_mmol_l": 3.1
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• A1C ↔ eAG — Convert A1C percent to estimated average glucose, or the reverse, using Nathan/ADAG.

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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /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.