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LDL Cholesterol

Lipids

Bad cholesterolLDL-CLow-density lipoprotein cholesterol

Review status

Currently under review

Pending specialist review and validation.

What it shows

LDL cholesterol measures the amount of cholesterol carried by low-density lipoproteins in your blood. These particles transport cholesterol to tissues throughout your body. When there is more LDL cholesterol than your body needs, it can build up in artery walls and contribute to plaque formation.

This test is usually part of a lipid panel. LDL cholesterol can be measured directly or estimated from other lipid results. Fasting is not always required, but your clinician may advise fasting depending on the method used and your clinical situation.

Why it matters

LDL cholesterol is a major contributor to atherosclerotic cardiovascular disease, which includes heart attack and stroke. Checking it helps your care team estimate your risk, decide on prevention strategies, and track how well treatment is working.

Clinicians use LDL cholesterol to guide lifestyle advice and medications, to monitor therapy over time, and to evaluate inherited lipid conditions. It is commonly ordered for routine adult screening and more often if you have diabetes, high blood pressure, kidney disease, obesity, or a strong family history of early heart disease.

Understanding your results

Your LDL cholesterol is interpreted alongside your age, blood pressure, smoking status, diabetes, other lipid values, and personal or family history. In general, lower LDL cholesterol is associated with lower cardiovascular risk. If your level is higher than expected, your clinician may recommend dietary changes, physical activity, weight management, and possibly medicines that lower LDL cholesterol.

If triglycerides are very high, calculated LDL cholesterol may be unreliable, and a direct measurement or an alternative calculation may be used. Nonfasting samples are often acceptable, but if results are unexpected, your clinician may repeat the test under fasting conditions. Discuss any changes in results with your care team so that next steps fit your health goals.

Reference ranges

1.63.4 mmol/L
All sexes
0 days – 18 years
-- mmol/L
All sexes
18 years – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact LDL Cholesterol

  • Fasting and recent meals

    Eating shortly before your blood draw can modestly change lipid measurements for some people. Follow the preparation instructions given by your clinician so results are comparable over time.

  • Triglycerides and calculation method

    When triglycerides are very high, formulas that estimate LDL cholesterol can be inaccurate. In such cases, a direct LDL measurement or an alternative calculation may be used.

  • Medications and supplements

    Statins, ezetimibe, PCSK9 inhibitors, and bile acid sequestrants lower LDL cholesterol. Some drugs such as certain steroids, progestins, and diuretics can raise it. Supplements like red yeast rice can also affect results.

  • Genetics and family history

    Inherited conditions such as familial hypercholesterolemia can keep LDL cholesterol high from a young age. A strong family history of early cardiovascular disease raises concern for genetic causes.

  • Thyroid, liver, kidney disease, and diabetes

    Low thyroid function, nephrotic syndrome, cholestatic liver disease, and poorly controlled diabetes can raise LDL cholesterol. Treating the underlying condition often improves levels.

  • Pregnancy and age

    Lipid levels naturally rise during pregnancy and tend to increase with age. Routine treatment decisions in pregnancy are individualized, and some medicines are avoided.

  • Recent illness or major events

    Acute illness, infection, or major surgery can temporarily change cholesterol levels. Your clinician may repeat testing after you have fully recovered.

  • Sample handling and lab method

    Different laboratory methods and instruments can yield slightly different results. Consistent testing at the same lab helps with reliable trend comparisons.

2026

References

  1. McGill University Health Centre. (2018, February 19). LDL Cholesterol (Task CD 316868). Laboratory reference ranges.
  2. Grundy, S. M., Stone, N. J., Bailey, A. L., Beam, C., Birtcher, K. K., Blumenthal, R. S., Braun, L. T., de Ferranti, S., Faiella-Tommasino, J., Forman, D. E., Goldberg, R., Heidenreich, P. A., Hlatky, M. A., Jones, D. W., Lloyd-Jones, D., Lopez-Pajares, N., Ndumele, C. E., Orringer, C. E., Peralta, C. A., ... Yeboah, J. (2019). 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol. Circulation, 139(25), e1082–e1143.