At a glance

Also known as

LDL; LDL-C; 'bad' cholesterol

Why get tested?

To determine risk of developing heart disease

When to get tested?

As part of a regular examination with a total cholesterol test or lipid profile or if your total cholesterol is high

Sample required?

A blood sample drawn from a vein in the arm or from a fingerprick (capillary).
Measurement of LDL cholesterol generally requires an 8-12 hour fast before the sample is taken.

What is being tested?

LDL is a type of lipoprotein that carries cholesterol in the blood. LDL cholesterol (LDL-C) is considered to be undesirable because it deposits excess cholesterol in the walls of blood vessels and contributes to 'narrowing of the arteries' and heart disease. Hence LDL cholesterol is often termed 'bad' cholesterol. The test for LDL cholesterol measures the amount of cholesterol bound to LDL in blood.

How is the sample collected for testing?

The test for LDL cholesterol uses a blood sample. Most often, the blood sample is collected by venipuncture (using a needle to collect blood from a vein in the arm). Measurement of LDL cholesterol generally requires an 8-12 hour fast before the sample is taken.

The Test

How is it used?

The test for LDL cholesterol is used to predict your risk of developing heart disease. Of all the forms of cholesterol in the blood, the LDL cholesterol is considered the most important form in determining risk of heart disease. Treatment decisions are often based on LDL cholesterol values.

When is it requested?

LDL cholesterol levels are ordered as part a lipid profile, along with total cholesterol, HDL cholesterol (HDL-C), and triglycerides. This profile may be used as a screening test in a healthy person as part of a routine physical examination. A lipid profile may be requested on someone who has had a high screening cholesterol to see if the total cholesterol is elevated because of too much LDL-C and on those who have one or more major risk factors for heart disease. LDL-C may also be requested at regular intervals to evaluate the success of lipid-lowering lifestyle changes such as diet and exercise or to determine the effectiveness of drug therapy such as statins.

What does the test result mean?

Elevated levels of LDL-C indicate risk for heart disease. Treatment (with diet and drugs) for high LDL aims to lower LDL-C to a target value of less than 2.5 mmol/L.

In some very high risk people the target is less than 2.0 mmol/L. This is especially important if you have other risk factors for heart disease. Risk factors include cigarette smoking, hypertension, low HDL-C (< 1 mmol/L), family history, being overweight, microalbuminuria and/or renal impairment, diabetes, impaired fasting glucose or glucose intolerance and over the age of 45 years.

About Reference or “Normal” Ranges

Is there anything else I should know?

Measurement of LDL-C generally requires an 8 - 12 hour fast — meaning that you must not eat or drink anything that has calories for 12 hours before your blood is drawn. You may drink water. This is because LDL-C is usually calculated from the results of other tests, including triglycerides, that require fasting. This result may be reported as 'calculated LDL-C'. Some laboratories can measure LDL-C directly using a special technology and fasting is not necessary. This test is usually called 'direct LDL-C'.

LDL cholesterol should be measured when a person is healthy. LDL cholesterol is temporarily low during acute illness, immediately following a heart attack, or during stress (like from surgery or an accident). You should wait at least six weeks after any illness to have LDL cholesterol measured.

In women, cholesterol is high during pregnancy. Women should wait at least six weeks after the baby is born to have LDL cholesterol measured.

Common Questions

What treatments are recommended for high LDL cholesterol levels?

The first step in treating high LDL cholesterol is adoption of a diet low in saturated fats. If diet alone does not adequately lower LDL-C, drugs may be prescribed.

How much will LDL cholesterol change as a result of lifestyle changes, like exercise or diet?

Adoption of a diet low in saturated fat (less than 6% of calories from saturated fat) will usually lower LDL cholesterol by about 10%.

Should someone with a family history of high LDL cholesterol levels be tested at a young age?

Often, children of individuals who have a family history of high LDL cholesterol and heart disease are screened for total cholesterol and LDL cholesterol at a young age. However, there is considerable controversy about whether children under 18 years of age should be treated for high LDL cholesterol since treatments may stunt growth and development.

Last Review Date: August 23, 2013