LDL cholesterol levels: what do they tell you about your vascular health?

This test measures the concentration of LDL cholesterol in your blood, expressed in mmol/L. In most laboratories, LDL is not measured directly but calculated from total cholesterol, HDL, and triglycerides (the Friedewald formula). With very high triglycerides, a direct LDL measurement may be more accurate.

The desirable upper limit varies by risk profile: for healthy adults without risk factors, < 3.0 mmol/L applies. With diabetes, a history of cardiovascular disease, or a high calculated risk, the target is < 1.8 mmol/L or even < 1.4 mmol/L. Fasting (10–12 hours) is recommended for the most accurate calculation.

LDL cholesterol is the best-established modifiable risk factor for atherosclerotic cardiovascular disease. Every 1 mmol/L reduction in LDL reduces the risk of a cardiovascular event by approximately 20–25%. This effect is independent of how the reduction is achieved — through diet, exercise, or medication.

In familial hypercholesterolaemia (FH) — a hereditary condition affecting approximately 1 in 250 people — LDL is elevated from a young age, significantly increasing the risk of early cardiovascular disease. Early detection and treatment are crucial.

LDL is measured as part of a lipid profile. It is recommended with elevated total cholesterol, risk factors for cardiovascular disease (smoking, hypertension, diabetes, obesity, family history), and when monitoring statin use. With a family history of very high cholesterol or premature heart disease, screening for familial hypercholesterolaemia is sensible. Fasting (10–12 hours) is recommended.