Is LDL the only number that matters?

No. Clinicians look at LDL alongside HDL, triglycerides, non-HDL cholesterol, sometimes ApoB and Lp(a), and other risk factors such as blood pressure and smoking.

Biomarker · Cardiovascular

LDL cholesterol

LDL cholesterol is the main cholesterol measure used to assess cardiovascular risk. Learn what LDL-C is, how it's measured and what affects your result.

Written by LON6EVITY Editorial Team · Last updated 2026-09-29

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Overview

LDL cholesterol (LDL-C) is the amount of cholesterol carried in low-density lipoprotein particles. It is often called 'bad' cholesterol because high levels contribute to plaque build-up in arteries.

Why it matters

LDL cholesterol is the primary lipid target in most cardiovascular prevention guidelines, including the ESC/EAS dyslipidaemia guidelines. Lowering LDL cholesterol is associated with lower risk of heart attack and stroke.

What it measures

Many labs calculate LDL-C from total cholesterol, HDL and triglycerides; others measure it directly. Calculated values can be less accurate when triglycerides are very high.

Higher results

High LDL-C can result from diet, genetics (such as familial hypercholesterolaemia), weight, hypothyroidism and other factors. What counts as 'too high' depends on your overall cardiovascular risk.

Lower results

Low LDL-C is generally favourable. Unusually low values without treatment can occasionally reflect other conditions and are worth mentioning to your clinician.

How the test is performed

LDL is part of a lipid panel from a blood sample. Some labs require fasting for 9–12 hours; others do not.

Reference ranges

NHS general guide for healthy adults	≤ 3 mmol/L

Reference ranges and targets differ between laboratories, units and guidelines, and depend on age, sex, method and your overall clinical picture. A single result is not a diagnosis — interpret it with a qualified clinician. Guideline targets become lower as estimated cardiovascular risk rises.

Factors that can affect the result

Saturated fat intake
Genetics
Body weight and activity
Hypothyroidism
Medications (e.g. statins lower LDL)

Questions people commonly ask

Is LDL the only number that matters?: No. Clinicians look at LDL alongside HDL, triglycerides, non-HDL cholesterol, sometimes ApoB and Lp(a), and other risk factors such as blood pressure and smoking.

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Sources

LDL: The "Bad" Cholesterol. MedlinePlus, U.S. National Library of Medicine.
Cholesterol Levels. MedlinePlus, U.S. National Library of Medicine.
Cholesterol levels. NHS.
2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. European Society of Cardiology / European Atherosclerosis Society (Mach F et al.), Eur Heart J, 2020.