LDL cholesterol (Friedewald)
Calculated LDL-C in mmol/L, read against ESC/EAS 2019 targets
- ESC/EAS 2019 dyslipidaemia guideline
Sources last checked: 2026-10-13
LDL cholesterol (Friedewald)
Calculated LDL-C in mmol/L, read against ESC/EAS 2019 targets
Invalid when triglycerides exceed 4.5 mmol/L and increasingly inaccurate at very low LDL-C or in non-fasting hypertriglyceridaemia; directly measured LDL-C is the more reliable value there. The LDL-C goal depends on the patient's total cardiovascular risk category.
Interpretation
| < 1.4 mmol/L | Meets the ESC/EAS 2019 goal for very-high-risk patients (< 1.4 mmol/L and ≥ 50 % reduction from baseline). At low LDL-C the Friedewald estimate becomes less accurate. |
|---|---|
| 1.4 to < 1.8 mmol/L | Meets the high-risk goal (< 1.8 mmol/L), above the very-high-risk goal. |
| 1.8 to < 2.6 mmol/L | Meets the moderate-risk goal (< 2.6 mmol/L), above the high- and very-high-risk goals. |
| 2.6 to < 3.0 mmol/L | Meets the low-risk goal (< 3.0 mmol/L) only. |
| 3.0 to < 4.9 mmol/L | Above every ESC/EAS 2019 LDL-C goal. Whether treatment is needed depends on total CV risk (e.g. SCORE2). |
| ≥ 4.9 mmol/L | Markedly elevated: LDL-C > 4.9 mmol/L alone places a person in the high-risk category (ESC 2019/2021). Familial hypercholesterolaemia is among the possible causes. |
What is the LDL cholesterol (Friedewald)?
The Friedewald equation estimates LDL cholesterol from a standard lipid panel by subtracting HDL cholesterol and an estimate of VLDL cholesterol (triglycerides ÷ 2.2 in mmol/L) from total cholesterol. Friedewald, Levy and Fredrickson published it in 1972, validated against ultracentrifugation. It remains the default calculated LDL-C in many European laboratories, and the ESC/EAS 2019 guideline sets its treatment goals in mmol/L LDL-C.
When to use it
- Estimating LDL-C when the lab report gives only total cholesterol, HDL-C and triglycerides.
- Checking LDL-C against the ESC/EAS 2019 risk-based goals during lipid-lowering therapy.
- Identifying markedly raised LDL-C, which is compatible with familial hypercholesterolaemia.
When not to use it
- Triglycerides above 4.5 mmol/L (400 mg/dL) — the equation is invalid.
- Type III dysbetalipoproteinaemia or chylomicronaemia.
- Very low LDL-C on intensive therapy, where the estimate drifts — direct LDL-C or non-HDL-C is more reliable.
How it is calculated
LDL-C = TC − HDL-C − TG / 2.2 (all in mmol/L) mg/dL version: LDL-C = TC − HDL-C − TG / 5 Not valid if TG > 4.5 mmol/L (400 mg/dL)
Clinical pearls and limitations
- Invalid when triglycerides exceed 4.5 mmol/L and increasingly inaccurate at very low LDL-C or in non-fasting hypertriglyceridaemia; directly measured LDL-C is the more reliable value there. The LDL-C goal depends on the patient's total cardiovascular risk category.
- The divisor is 2.2 in mmol/L and 5 in mg/dL — mixing units is the most common error.
- Non-HDL cholesterol (TC − HDL-C) needs no fasting and no triglyceride correction; the ESC uses it as a secondary target.
- LDL-C goals (ESC/EAS 2019): very high risk < 1.4, high < 1.8, moderate < 2.6, low < 3.0 mmol/L.
- A single LDL-C > 4.9 mmol/L is itself a high-risk feature.
Frequently asked questions
What is the Friedewald formula in mmol/L?
LDL-C = total cholesterol − HDL-C − triglycerides / 2.2, all in mmol/L.
When is the Friedewald formula invalid?
When triglycerides exceed 4.5 mmol/L (400 mg/dL), and in type III hyperlipoproteinaemia. It is also less accurate at very low LDL-C.
What is the LDL target for very-high-risk patients in Europe?
The ESC/EAS 2019 guideline recommends LDL-C < 1.4 mmol/L (55 mg/dL) and at least a 50 % reduction from baseline.
How do I convert LDL-C from mg/dL to mmol/L?
Divide mg/dL by 38.67 (e.g. 100 mg/dL ≈ 2.6 mmol/L).
Evidence and guidelines
- Primary source: Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem 1972;18(6):499-502.
- Mach F et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J 2020;41:111-188.
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