Cholesterol

Does this test have other names?

Total blood cholesterol, serum cholesterol

What is this test?

This test measures the amount of cholesterol in your blood. This helps your healthcare provider figure out your risk for heart disease.

Cholesterol is a waxy fat-like substance found in all of your body's cells, where it plays an important role. But your body can have too much cholesterol if you eat the wrong types of foods. These include fried foods and foods with saturated or trans fats. Some health conditions can also make your cholesterol level too high.

If you have too much cholesterol in your blood, it can stick to the walls of the arteries in your heart (coronary arteries). The extra cholesterol can make your blood vessels narrower (atherosclerosis). This narrowing makes it harder to get enough blood through your blood vessels. If your heart muscles don't get enough blood, you may be at risk for a heart attack. Cholesterol can also stick to the walls of arteries elsewhere in your body. This can cause other types of artery diseases. 

The American Heart Association recommends that all adults ages 20 and older have their cholesterol and other traditional risk factors checked every 4 to 6 years. Work with your healthcare provider to find out your risk for cardiovascular disease and stroke.

Why do I need this test?

You may have this test as part of your regular health checkup. You may have this test done more often if you are at risk for heart disease or have other health problems caused by high cholesterol.

Here are some common reasons for the test:

• You have risk factors for heart disease. These include older age, obesity, family history of heart disease, high blood pressure, smoking, and diabetes.

• You have a condition that may be closely linked to high cholesterol. This includes diabetes, alcoholism, and thyroid, liver, or kidney disease.

• You eat a diet high in cholesterol and fats.

You may also have this test if you had high or borderline cholesterol on an earlier blood test. Your healthcare provider may want to check to see whether medicine, diet, exercise, and other lifestyle changes are helping lower your cholesterol.

What other tests might I have along with this test?

You may need other blood tests to find out your HDL ("good") cholesterol, LDL ("bad") cholesterol, and triglyceride levels. This combination of blood tests is called a lipoprotein profile or a lipid profile.

What do my test results mean?

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

Total cholesterol is measured in milligrams per deciliter (mg/dL). This is what your number may mean:

• Less than 200 mg/dL is a good number. Your risk of heart disease may be low.

• 200 mg/dL to 239 mg/dL is borderline high. You may be at some risk for heart disease.

• 240 mg/dL or higher means your cholesterol is high. Your risk for heart disease may be higher than that of a person with normal cholesterol.

Keep in mind that your risk for heart disease based on your total cholesterol greatly depends on your HDL and LDL levels and other risk factors.

High cholesterol may be linked to these conditions:

• Inherited diseases that cause high cholesterol

• Gallbladder stones

• Kidney failure

• Cancer of the pancreas or prostate

• Low thyroid hormone

• Diabetes

• Obesity

Cholesterol levels below 140 mg/dL may happen with:

• Very healthy lifestyle and diet

• Severe liver disease

• High thyroid hormone

• Severe burns

• White blood cell cancers

• Poor nutrition

• Some types of anemia

• Short-term illness or infection

• Chronic lung disease

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?

Your diet, age, alcohol use, and other lifestyle choices may affect your results. Many medicines may also affect your results. Pregnancy may also affect your results. Having a heart attack in the last 3 months will also affect your results.

How do I get ready for this test?

You should keep to your regular diet and not drink alcohol for at least 2 days before this test. You will be asked to not eat or drink anything but water for a certain amount of time before the test. This test is usually done in the morning after you fast overnight. If you take medicines in the morning, ask your healthcare provider if you should take your pills.

In addition, 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.