{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"ldl-cholesterol"},"result":{"entity_type":"calculator","id":"ldl-cholesterol","calculator_id":"ldl-cholesterol","canonical_url":"https://tttkmbb.com/medical/ldl-cholesterol","name":"LDL Cholesterol Calculator","title":"LDL Cholesterol Calculator – Friedewald Equation and Non-HDL Cholesterol","category":"medical","category_name":"Medical & Clinical","tool_name":"calculate_ldl_cholesterol","featured_mcp_tool":false,"description":"Calculates LDL cholesterol from total cholesterol, HDL and triglycerides with the Friedewald equation (mg/dL or mmol/L), plus non-HDL cholesterol and the NCEP LDL category.","use_when":"You have a fasting lipid panel without a direct LDL measurement and need the calculated LDL or non-HDL cholesterol.","do_not_use_when":"Triglycerides exceed 400 mg/dL (4.5 mmol/L) or the sample was non-fasting; Friedewald is invalid there and a direct LDL assay or the Martin/Hopkins or Sampson equations are used instead.","inputs":[{"name":"total_cholesterol","label":"Total cholesterol","type":"number","required":true,"max":2000,"exclusive_min":0,"description":"Total cholesterol in the chosen unit.","example":200},{"name":"hdl_cholesterol","label":"HDL cholesterol","type":"number","required":true,"max":500,"exclusive_min":0,"description":"HDL cholesterol in the chosen unit.","example":50},{"name":"triglycerides","label":"Triglycerides","type":"number","required":true,"max":5000,"exclusive_min":0,"description":"Fasting triglycerides in the chosen unit.","example":150},{"name":"unit","label":"Unit","type":"enum","required":false,"default":"mg_dl","values":[{"value":"mg_dl","label":"mg/dL","aliases":["mg/dl","mgdl"]},{"value":"mmol_l","label":"mmol/L","aliases":["mmol/l","mmol"]}],"description":"Unit shared by all three inputs.","example":"mg_dl"}],"outputs":[{"name":"ldl_cholesterol","label":"LDL cholesterol (Friedewald)","type":"number","decimals":2,"description":"Calculated LDL in the input unit."},{"name":"non_hdl_cholesterol","label":"Non-HDL cholesterol","type":"number","decimals":2,"description":"Total − HDL, in the input unit."},{"name":"unit","label":"Unit","type":"string","decimals":4,"description":"Unit of the two values above."},{"name":"ldl_cholesterol_mg_dl","label":"LDL","type":"number","unit":"mg/dL","decimals":1,"description":"LDL in mg/dL."},{"name":"ldl_cholesterol_mmol_l","label":"LDL","type":"number","unit":"mmol/L","decimals":2,"description":"LDL in mmol/L (mg/dL × 0.02586)."},{"name":"ldl_category","label":"LDL category (NCEP ATP III)","type":"string","decimals":4,"description":"Optimal <100, near optimal 100–129, borderline high 130–159, high 160–189, very high ≥190 mg/dL."}],"input_schema":{"type":"object","properties":{"total_cholesterol":{"description":"Total cholesterol in the chosen unit.","type":"number","maximum":2000,"exclusiveMinimum":0,"examples":[200]},"hdl_cholesterol":{"description":"HDL cholesterol in the chosen unit.","type":"number","maximum":500,"exclusiveMinimum":0,"examples":[50]},"triglycerides":{"description":"Fasting triglycerides in the chosen unit.","type":"number","maximum":5000,"exclusiveMinimum":0,"examples":[150]},"unit":{"description":"Unit shared by all three inputs.","type":"string","enum":["mg_dl","mmol_l"],"default":"mg_dl","examples":["mg_dl"]}},"additionalProperties":false,"required":["total_cholesterol","hdl_cholesterol","triglycerides"]},"output_schema":{"type":"object","properties":{"ldl_cholesterol":{"description":"Calculated LDL in the input unit.","type":"number"},"non_hdl_cholesterol":{"description":"Total − HDL, in the input unit.","type":"number"},"unit":{"description":"Unit of the two values above.","type":"string"},"ldl_cholesterol_mg_dl":{"description":"LDL in mg/dL. Unit: mg/dL.","type":"number","x-unit":"mg/dL"},"ldl_cholesterol_mmol_l":{"description":"LDL in mmol/L (mg/dL × 0.02586). Unit: mmol/L.","type":"number","x-unit":"mmol/L"},"ldl_category":{"description":"Optimal <100, near optimal 100–129, borderline high 130–159, high 160–189, very high ≥190 mg/dL.","type":"string"}}},"formula":"LDL = total_cholesterol − hdl_cholesterol − triglycerides / 5 (mg/dL) or − triglycerides / 2.2 (mmol/L); non-HDL = total_cholesterol − hdl_cholesterol","method":"Friedewald (1972) assumes VLDL cholesterol ≈ TG/5 in fasting samples; accuracy falls when TG is 200–400 mg/dL or LDL is below 70 mg/dL. Results are informational only and not a substitute for clinical judgement or medical advice.","sources":[{"name":"Friedewald WT, Levy RI, Fredrickson DS (1972) Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge, Clin Chem 18:499-502","url":"https://pubmed.ncbi.nlm.nih.gov/4337382/","type":"peer_reviewed","retrieved_at":"2026-09-24"},{"name":"American Heart Association – What your cholesterol levels mean","url":"https://www.heart.org/en/health-topics/cholesterol/about-cholesterol/what-your-cholesterol-levels-mean","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"TC 200, HDL 50, TG 150 mg/dL","inputs":{"total_cholesterol":200,"hdl_cholesterol":50,"triglycerides":150,"unit":"mg_dl"},"expected":{"ldl_cholesterol":120,"non_hdl_cholesterol":150,"ldl_cholesterol_mmol_l":3.1,"ldl_category":"Near optimal (100–129 mg/dL)"},"url":"https://tttkmbb.com/api/v1/calculate/ldl-cholesterol?total_cholesterol=200&hdl_cholesterol=50&triglycerides=150&unit=mg_dl"},{"name":"TC 5.2, HDL 1.3, TG 1.5 mmol/L","inputs":{"total_cholesterol":5.2,"hdl_cholesterol":1.3,"triglycerides":1.5,"unit":"mmol_l"},"expected":{"ldl_cholesterol":3.22,"non_hdl_cholesterol":3.9,"ldl_cholesterol_mg_dl":124.4},"url":"https://tttkmbb.com/api/v1/calculate/ldl-cholesterol?total_cholesterol=5.2&hdl_cholesterol=1.3&triglycerides=1.5&unit=mmol_l"}],"faq":[{"q":"Why is Friedewald invalid at high triglycerides?","a":"The TG/5 term assumes a fixed VLDL composition; above 400 mg/dL (and in chylomicronaemia) it overestimates VLDL and underestimates LDL, so the calculator returns an error instead of a number."},{"q":"What is non-HDL cholesterol for?","a":"It captures all atherogenic lipoproteins (LDL, VLDL, IDL, Lp(a)) and stays valid in non-fasting samples; targets are usually 30 mg/dL (0.8 mmol/L) above the LDL target."}],"tags":["ldl cholesterol","friedewald","non-hdl cholesterol","lipid panel","vldl"],"related":[{"calculator_id":"cholesterol-unit-conversion","reason":"Convert lipid values between mg/dL and mmol/L."},{"calculator_id":"bmi","reason":"Weight status alongside lipid results."}],"links":{"html":"https://tttkmbb.com/medical/ldl-cholesterol","markdown":"https://tttkmbb.com/medical/ldl-cholesterol.md","json":"https://tttkmbb.com/medical/ldl-cholesterol.json","api":"https://tttkmbb.com/api/v1/calculate/ldl-cholesterol","schema":"https://tttkmbb.com/api/v1/calculators/ldl-cholesterol","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:49:42Z","next_actions":[{"tool":"run_calculator","calculator_id":"ldl-cholesterol","reason":"Run LDL Cholesterol Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/medical/ldl-cholesterol.md"}}