LDL Cholesterol

Does this test have other names?

Low-density lipoprotein-cholesterol, LDL-C

What is this test?

This test measures the amount of low-density lipoprotein-cholesterol (LDL-C) in your blood.

LDL cholesterol is often called "bad" cholesterol because it causes plaque to build up inside your arteries and leads to heart disease.

Cholesterol screening is advised every 4 to 6 years for adults ages 20 and older who are at low risk for heart disease. You may need to have your blood tested more often if you have risk factors for heart disease or stroke. Talk with your healthcare provider. LDL cholesterol is one of a group of lipoproteins that can indicate heart disease, so this test is used to help diagnose it.

Lowering LDL-C levels can help prevent heart disease.

Why do I need this test?

You may need this test as part of a routine exam to check for high cholesterol.

You may also have this test if you already have heart disease caused by high cholesterol. The test can help your healthcare provider find out how well your treatment is working.

What other tests might I have along with this test?

Your healthcare provider may also order other blood tests to measure the levels of various fats in your blood. These include:

• Total cholesterol

• Triglycerides

• High-density lipoprotein, or HDL

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in milligrams per deciliter (mg/dL). The normal range of LDL-C is 50 to 100 mg/dL. Depending on all your risk factors, in general:

• Less than 100 is optimal

• 100 to 129 mg/dL is near or just above optimal

• 130 to 159 mg/dL is borderline high

• 160 to 189 mg/dL is high

• 190 mg/dL and over is very high

The optimal level of LDL has changed over time and depends on all your risk factors. Generally, a LDL cholesterol level of 100 mg/dL may be a good goal. A level below 70 mg/dL is considered best for people who have diabetes or heart disease risk factors.

High cholesterol is only one of the big risk factors for heart disease and stroke. Other things that can increase your risk include:

• Smoking

• Having diabetes

• Not exercising

• Having high blood pressure

• Being older in age

• Eating an unhealthy diet

To help find your overall risk, your provider may use a risk calculator. It takes into account your cholesterol level and other risk factors. Ask your healthcare provider about your 10-year risk if you are older than age 40 or your lifetime risk if you are age 20 to 39. Depending on all your risk factors, your healthcare provider will talk with you about your cholesterol results and what is important for overall health.

It's possible to have extremely low levels of LDL-C, but this is rare. This condition is usually a sign of a problem processing vitamins A, D, E, and K.

If your levels of LDL-C are very high, the condition is called dyslipidemia. High levels may mean that you have an imbalance in your diet. But the condition is often genetic and known as familial hypercholesterolemia.

If your cholesterol level is higher than normal, your healthcare provider will tell you how to lower your level. Changing your lifestyle habits and taking medicines to reduce LDL levels may help you lower your risk for heart disease. It can also help you manage the condition if you already have it.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

Smoking cigarettes can increase LDL-C levels. Stress, certain minor ailments, and some medicines can also affect your results.

How do I get ready for this test?

Testing of your cholesterol level does not need fasting in most cases. But your healthcare provider may ask you to not eat or drink anything but water for a certain time before having the test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.