Facts you should know about cholesterol tests
- Cholesterol is a naturally occurring substance in the body that is an important part of normal body function.
- Cholesterol has two main types: HDL, or good cholesterol, that protects against heart disease, stroke and peripheral vascular disease; and LD, or bad, cholesterol, which increases the risk of these conditions.
- Cholesterol tests measure total cholesterol as well as HDL and LDL levels in the blood. Triglycerides, another type of fat present in the bloodstream, may also be measured.
- Cholesterol tests are usually ordered and blood drawn in a doctor's office. There are also home test kits available. It is important to be fasting for the tests to be accurate. Typically, a fasting test is performed first thing in the morning before the individual has eaten anything for the day. Fasting typically requires 12 hours without food. Water, plain tea or coffee are permitted, and hydration is required. No other liquids are acceptable during the fasting period. Patients cannot add sugar, artificial sweeteners, cream, or milk to drinks.
- If you take OTC, prescription, or herbal supplements discuss these with your doctor prior to the test.
- Cholesterol test results should be discussed with the health-care professional to determine if treatment of high cholesterol is necessary to decrease the risk of heart disease and stroke.
What is cholesterol?
Cholesterol is a naturally occurring fat that the body needs to produce important structures and chemicals. It is one of the main components of cell membranes, the outer lining that protects the internal structures that make body cells work and function properly. Cholesterol is also a building block for many of the hormones in the body including mineralocorticoids that control electrolyte levels in the body, glucocorticoids involved in carbohydrate metabolism, and sex hormones including testosterone, estrogen, and progesterone. Cholesterol is one of the building blocks that assists in forming vitamin D in the body. Vitamin D is responsible for calcium metabolism in the body.
There are two important types of cholesterol, high density lipoprotein (HDL) and low density lipoprotein (LDL). LDL is the bad cholesterol that deposits in arteries when too much is present. HDL is considered the good cholesterol because it can bind to LDL cholesterol and return it to the liver where it can be removed from the body.
While most of the cholesterol in the body is obtained through the foods we eat, it is also produced in the liver to meet the body's demands. The body attempts to regulate the amount of total cholesterol, but when too much cholesterol is present, the excess can be deposited in arteries throughout the body. This leads to artery narrowing and increases the risk of heart attack, stroke, and peripheral vascular disease. Elevated LDL levels increase the risk of these diseases, and elevated HDL levels decrease the risk.
What does a cholesterol test measure?
Cholesterol tests are blood tests that measure the amount of cholesterol in the body. The health care professional may order only a cholesterol test with results showing:
- The total cholesterol,
- HDL, and
- LDL levels.
In addition to cholesterol level, the health-care professional also may order a lipid profile test. The lipid profile test will also measure triglyceride levels and another fatty substance found in the blood.
How do I prepare for a cholesterol test?
For the best and most accurate results, it is important to fast for many hours before the cholesterol blood test is taken. Each laboratory has its own guidelines for not eating, and the fast may range from 9-16 hours. It is acceptable to drink water.
Do I need to call my doctor for my test results?
It usually takes a day or two from the time the blood is drawn until your health care professional receives the results of the cholesterol test. Ideally, the health care professional will contact you with those results and explain their significance. However, if you have not been contacted in a short period of time, it is reasonable to contact your health care professional and ask for the test results.
There are home cholesterol test kits available that have been U.S. FDA approved, but their accuracy is not necessarily as good as that of a certified laboratory. These tests usually measure total cholesterol only, but some also can measure HDL, LDL, and cholesterol. If you use one of the home kits, it is wise to discuss the results with your health-care professional.
The purpose of the cholesterol blood test is to determine whether treatment is needed for high cholesterol. That treatment may include dietary and lifestyle modifications, medications, or both to control cholesterol levels and decrease the risk of heart disease, stroke, and peripheral vascular disease.
How do I interpret my cholesterol test results?
Cholesterol levels are but one of the risk factors for heart disease, stroke, and peripheral vascular disease. It is important to control cholesterol levels to minimize risk just as it is important to control diabetes, high blood pressure, and avoid smoking.
Guidelines for cholesterol levels have been developed by many health organizations including the American Heart Association. It is important to remember that tests may need to be repeated over time to help monitor treatment and disease risk prevention.
|Less than 200 mg/dL: desirable|
|200-239 mg/dL: borderline high risk|
|240 mg/dL and over: high risk|
|HDL (high density lipoprotein)|
|Less than 40 mg/dL (men), less than 50 mg/dL (women): increased risk of heart disease|
|Greater than 60 mg/dL: some protection against heart disease|
|LDL (low density lipoprotein)|
|Less than 100 mg/dL: optimal|
|100-129 mg/dL: near optimal/above optimal|
|130-159 mg/dL: borderline high|
|160-189 mg/dL: high|
|190 mg/dL and above: very high|
|Less than 150 mg/dL: normal|
|150-199 mg/dL: borderline to high|
|200-499 mg/dL: high|
|Above 500 mg/dL: very high|
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American Heart Association. What Your Cholesterol Levels Mean.