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To screen for risk of developing heart disease; to monitor effectiveness of lipid-lowering therapy
Screening: as part of a regular health exam with a lipid profile when no risk factors for heart disease are present; adults should be tested once every four to six years; children, teens, and young adults should be tested once between the ages of 9 and 11 and then again between the ages of 17 and 21.
Monitoring: may be done more frequently and at regular intervals when risk factors for heart disease are present, when prior results showed high risk levels, and/or when undergoing treatment for unhealthy lipid levels
Most often, a blood sample is collected from a vein in the arm. Sometimes cholesterol is measured using a drop of blood collected by puncturing the skin on a finger. A fingerstick sample is typically used when cholesterol is being measured on a portable testing device, for example, at a health fair.
Cholesterol tests typically require fasting for 9-12 hours before the test; only water is permitted. Your healthcare practitioner may decide that you may be tested without fasting. Follow any instructions you are given and tell the person drawing your blood whether or not you have fasted. For youths without risk factors, testing may be done without fasting.
Cholesterol is a substance (a steroid) that is essential for life. It forms the membranes for cells in all organs and tissues in the body. It is used to make hormones that are essential for development, growth, and reproduction. It forms bile acids that are needed to absorb nutrients from food. The test for cholesterol measures total cholesterol that is carried in the blood by lipoproteins.
A small amount of cholesterol circulates in the blood in complex particles called lipoproteins. Each particle contains a combination of protein, cholesterol, triglyceride, and phospholipid molecules and the particles are classified by their density into high-density lipoproteins (HDL), low-density lipoproteins (LDL), and very low-density lipoproteins (VLDL). HDL-C particles, sometimes called "good" cholesterol, carry excess cholesterol away for disposal and LDL-C particles, or "bad" cholesterol, deposit cholesterol in tissues and organs.
Monitoring and maintaining healthy levels of cholesterol is important for staying healthy. The body produces the cholesterol needed to work properly, but the source for some cholesterol is diet. If an individual has an inherited predisposition for high cholesterol levels or eats too much of the foods that are high in saturated fats and trans unsaturated fats (trans fats), then the level of cholesterol in that person's blood may increase and have a negative impact on the person's health. The extra cholesterol in the blood may be deposited in plaques on the walls of blood vessels. Plaques can narrow or eventually block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis) and increased risk of numerous health problems, including heart disease and stroke.
The test for total cholesterol is used alone or as part of a lipid profile to help predict an individual's risk of developing heart disease and to help make decisions about what treatment may be needed if there is borderline or high risk. As part of a lipid profile (which includes other tests for high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides), it may also be used to monitor the effectiveness of treatment once it is initiated.
Because high blood cholesterol has been associated with hardening of the arteries (atherosclerosis), heart disease, and a raised risk of death from heart attacks, cholesterol testing is considered a routine part of preventive healthcare.
Results of the cholesterol test and other components of the lipid profile are used along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Treatment options may include lifestyle changes such as diet or exercise programs or lipid-lowering drugs such as statins.
Cholesterol testing is recommended as a screening test to be done for all adults with no risk factors for heart disease at least once every four to six years. It is frequently done in conjunction with a routine physical exam.
Cholesterol is tested at more frequent intervals (often several times per year) when a person has one or more risk factors for heart disease. Major risk factors include:
Screening for high cholesterol as part of a lipid profile is recommended for children and young adults. They should be tested once between the ages of 9 and 11 and then again between the ages of 17 and 21. Earlier and more frequent screening with a lipid profile is recommended for children and youths who are at an increased risk of developing heart disease as adults. Some of the risk factors are similar to those in adults and include a family history of heart disease or health problems such as diabetes, high blood pressure, or being overweight. When the youth's body mass index (BMI) is at or above the 85th percentile, cholesterol testing is recommended. For an obese youth (one whose BMI is at or above the 95th percentile), laboratory tests to measure cholesterol levels may be recommended every 2 years.
High-risk children should have their first cholesterol test between 2 and 8 years of age, according to the American Academy of Pediatrics. Children younger than 2 years old are too young to be tested. If the initial results are not worrisome, the fasting test should be done again in three to five years.
As part of a lipid profile, total cholesterol tests may be ordered 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. Guidelines from the American College of Cardiology (ACC) and the American Heart Association (AHA) recommend that adults taking statins have a fasting lipid profile done 4 to 12 weeks after starting therapy and then every 3 to 12 months thereafter to assure that the drug is working.
In general, healthy lipid levels help to maintain a healthy heart and lower the risk of heart attack or stroke. A healthcare practitioner will take into consideration total cholesterol results and the other components of a lipid profile as well as other risk factors to help determine a person's overall risk of heart disease, whether treatment is necessary and, if so, which treatment will best help to lower the person's risk.
In 2002, the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) provided the guidelines for evaluating lipid levels and determining treatment. However, in 2013, the ACC and AHA issued guidelines for adults that made recommendations on who should receive cholesterol-lowing therapy. (For more details, see the Lipid Profile article).
However, use of the updated guidelines remains controversial. Many still use the older guidelines from the NCEP ATP III to evaluate lipid levels and cardiovascular disease (CVD) risk:
For adults, in a routine setting where testing is done to screen for risk, the test results are grouped in three categories of risk:
For children and adolescents:
For young adults:
In a treatment setting, testing is used to see how much cholesterol is decreasing as a result of treatment. The target value is usually based on LDL-C, according to ATP III.
Cholesterol should be measured when a person is not ill. Blood cholesterol is temporarily low during acute illness, immediately following a heart attack, or during stress (like from surgery or an accident). Wait at least six weeks after any illness to have cholesterol measured.
There is some debate about whether very low cholesterol is bad. Low cholesterol (less than 100 mg/dL (2.59 mmol/L)) is often seen when there is an existing problem like malnutrition, liver disease, or cancer. However there is no evidence that low cholesterol causes any of these problems.
Cholesterol is typically high during pregnancy. Women should wait at least six weeks after having a baby to have cholesterol measured.
Some drugs that are known to increase cholesterol levels include anabolic steroids, beta blockers, epinephrine, oral contraceptives, and vitamin D.
High cholesterol may be the result of an inherited disease or it may result from a diet high in saturated fats. For many people, it is caused by a combination of both a diet high in saturated and trans fats and an inherited tendency towards high cholesterol.
One treatment option is to adopt a lifestyle that will help lower your levels, one including exercise and a diet that is low in saturated fats and trans fat. If diet and exercise alone cannot lower cholesterol enough, drugs are often recommended and usually aim to lower LDL-C levels specifically. Sometimes, two different drugs are used together to treat people with extremely high cholesterol levels. The drug of choice differs for different people although the most commonly used lipid-lowering drugs are statins. Your healthcare practitioner will need to take into account your individual situation before prescribing any cholesterol-lowering drug.
High cholesterol increases your risk of a heart attack. The higher the cholesterol, the higher the risk. However, many other factors also affect your risk of a heart attack, such as smoking, diabetes, age, and high blood pressure. For more information on related risk factors, read the American Heart Association's article Understand Your Risk for High Cholesterol.
Cholesterol levels fluctuate over time. The measured cholesterol level may differ by as much as 10% from one month to another. It may go up sometimes or it may go down sometimes. These changes are called biological variation and they represent normal variability inherent in human metabolism.
Cholesterol levels fluctuate over time. A single measurement of cholesterol may not always reflect the "usual” cholesterol level. For this reason, you may have at least two different measurements several weeks to several months apart before beginning any kind of treatment.
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