What is cholesterol test

The cholesterol test also called a lipid panel or lipid profile, is a blood test that can measure the amount of cholesterol and triglycerides in your blood. More specifically, the cholesterol test measures total cholesterol that is carried in your blood by lipoproteins. A cholesterol test can help determine your risk of the buildup of plaques in your arteries that can lead to narrowed or blocked arteries throughout your body (atherosclerosis). 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.

A cholesterol test is an important tool. High cholesterol levels often are a significant risk factor for coronary artery disease.

Cholesterol is a soft, wax-like substance (a steroid) found in all parts of your body that is essential for life. Cholesterol forms the membranes for cells in all organs and tissues in the body. Cholesterol is used to make hormones that are essential for development, growth, and reproduction. Cholesterol forms bile acids that are needed to absorb nutrients from food. Your body needs a little bit of cholesterol to work properly. But too much cholesterol can clog your arteries and lead to heart disease.

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). High-density lipoproteins cholesterol (HDL-C) particles, sometimes called “good” cholesterol, carry excess cholesterol away for disposal and low-density lipoproteins cholesterol (LDL-C) particles, or “bad” cholesterol, because it deposits excess cholesterol in walls of blood vessels, which can contribute to atherosclerosis.

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.

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.

What is low-density lipoprotein cholesterol (LDL-C)?

LDL cholesterol also called low-density lipoprotein cholesterol (LDL-C) is sometimes called “bad” cholesterol. LDL can clog your arteries.

You want your LDL to be low. Too much LDL is linked to heart disease and stroke.

Your low-density lipoprotein cholesterol (LDL-C) is most often considered to be too high if it is 190 mg/dL or higher.

Levels between 70 and 189 mg/dL (3.9 and 10.5 mmol/l) are most often considered too high if:

• You have diabetes and are between ages 40 and 75
• You have diabetes and a high risk of heart disease
• You have a medium or high risk of heart disease

Health care providers have traditionally set a target level for your LDL cholesterol if you are being treated with medicines to lower your cholesterol.

• Some newer guidelines now suggest that providers no longer need to target a specific number for your LDL cholesterol. Higher strength medicines are used for the highest risk patients.
• However, some guidelines still recommend using specific targets.

What is HDL cholesterol (HDL-C)?

You want your HDL cholesterol or high-density lipoprotein cholesterol (HDL-C) to be high. Studies of both men and women have shown that the higher your HDL, the lower your risk of coronary artery disease. This is why HDL is sometimes referred to as “good” cholesterol.

• HDL cholesterol levels greater than 40 to 60 mg/dL (2.2 to 3.3 mmol/l) are desired.

What is VLDL cholesterol?

Very low-density lipoproteins (VLDL) contains the highest amount of triglycerides. VLDL is considered a type of “bad” cholesterol, because it helps cholesterol build up on the walls of arteries. Development of plaque on the arteries has been linked to high VLDL levels. It’s not easy to measure VLDL, so most of the time these levels are estimated based on triglyceride measurements.

• Normal VLDL levels are from 2 to 30 mg/dL (0.1 to 1.7 mmol/l).

Why do I need a cholesterol test?

Your doctor may order a cholesterol test as part of a routine exam, or if you have a family history of heart disease or one or more of the following risk factors:

• High blood pressure
• Type 2 diabetes
• Smoking
• Excess weight or obesity
• Lack of physical activity
• A diet high in saturated fat

Your age may also be a factor, because your risk for heart disease increases as you get older.

How accurate is cholesterol home test kit?

According to the U.S. Food and Drug Administration (FDA) home cholesterol test is about as accurate as the test your doctor uses, but you must follow the directions carefully ¹.

Total cholesterol tests vary in accuracy from brand to brand. Information about the test’s accuracy is printed on its package. Tests that say they are “traceable” to a program of the Centers for Disease Control and Prevention (CDC) may be more accurate than others.

How you do cholesterol home test?

You prick your finger with a lancet to get a drop of blood. Then put the drop of blood on a piece paper that contains special chemicals. The paper will change color depending on how much cholesterol is in your blood. Some cholesterol home testing kits use a small machine to tell you how much cholesterol there is in the sample.

What treatments are recommended if my lipid levels are unhealthy?

Adherence to a healthy lifestyle is an important part of maintaining heart health and in treating high cholesterol. This may mean you will need to change your lifestyle, specifically by adopting a diet low in saturated fat and trans unsaturated fats (trans fats), avoiding smoking, controlling high blood pressure and diabetes, and participating in moderate exercise. You may be referred to a dietician for advice in making dietary changes.

Your healthcare provider will talk to you about risks and benefits of drug therapy, based on the results of your low-density lipoprotein cholesterol (LDL-C) and possibly your calculated risk for atherosclerotic cardiovascular disease. There are several classes of drugs that are effective in lowering low-density lipoprotein cholesterol (LDL-C) or “bad” cholesterol. You may be prescribed one of these. Your low-density lipoprotein cholesterol (LDL-C) or “bad” cholesterol will be checked at regular intervals to assure that the drug is working. If the drug does not result in adequate reduction in your LDL cholesterol, your healthcare provider may increase the amount of drug or possibly add a second drug.

I had a screening test for cholesterol. It was less than 200 mg/dL (5.18 mmol/L). Do I need a lipid profile?

If your total cholesterol is below 200 (5.18 mmol/L) and you have no family history of heart disease or other risk factors, a full lipid profile may not be necessary. However, an HDL cholesterol (good cholesterol) measurement would be advisable to assure that you do not have a low high-density lipoprotein cholesterol (HDL-C). Many screening programs now offer both cholesterol and high-density lipoprotein cholesterol (HDL-C).

My lipid panel results came back with high triglycerides and no results for LDL-cholesterol. Why?

In most screening lipid panels, LDL cholesterol (bad cholesterol) is calculated from the other lipid measurements. However, the calculation is not valid if triglycerides are over 400 mg/dL (4.52 mmol/L). To determine LDL-C when triglycerides are over 400 mg/dL (4.52 mmol/L) requires special testing techniques such as a direct LDL-C test or a lipid ultracentrifugation test (sometimes called a beta-quantification test).

What is non-HDL-cholesterol?

Non-HDL-cholesterol (non-HDL-C) is calculated by subtracting your high-density lipoprotein cholesterol (HDL-C) result from your total cholesterol result. It represents the “atherogenic” cholesterol — the cholesterol that can build up in the arteries, form plaques, and cause narrowing of the vessels and blockages. Unlike calculation of LDL cholesterol (bad cholesterol) this calculation is not affected by high levels of triglycerides. Your non-HDL-cholesterol (non-HDL-C) result may be used to assess your risk for cardiovascular disease, especially if you have high triglycerides, since high non-HDL-C is associated with increased risk. As recommended by the National Cholesterol Education Program, Adult Treatment Panel III, if you have high triglycerides (greater than 200 mg/dL), the non-HDL-C result can be used as a secondary target of treatments such as lifestyle changes and drugs that aim to lower lipid levels.

What is a low-density lipoprotein particle number (LDL-P) test?

Low-density lipoprotein particle number (LDL-P) is a test that measures the number of LDL particles, rather than measuring the amount of LDL-cholesterol. For many people, the LDL-C test is a good indicator of risk of cardiovascular disease. However, research has found that some people with healthy levels of LDL-C still have increased risk of cardiovascular disease. Similarly, individuals with some chronic conditions such as diabetes may have increased risk though their LDL-C is at a healthy level. For these populations, it has been suggested that the number of LDL particles, and their size, might be an additional factor to consider when determining their cardiovascular disease risk.

Is there anything else I need to know about my cholesterol levels?

High cholesterol can lead to heart disease, the number one cause of death in the United States. While some risk factors for cholesterol, such as age and heredity, are beyond your control, there are actions you can take to lower your LDL levels and reduce your risk, including:

• Eating a healthy diet. Reducing or avoiding foods high in saturated fat and cholesterol can help reduce the cholesterol levels in your blood.
• Losing weight. Being overweight can increase your cholesterol and risk for heart disease.
• Staying active. Regular exercise may help lower your LDL (bad) cholesterol levels and raise your HDL (good) cholesterol levels. It may also help you lose weight.

Talk to your health care provider before making any major change in your diet or exercise routine.

When is cholesterol test ordered?

High cholesterol usually causes no signs or symptoms. Cholesterol blood tests are done to help you and your health care provider better understand your risk for heart disease, stroke, and other problems caused by narrowed or blocked arteries.

Everyone should have their first screening test by age 35 for men, and age 45 for women. Some guidelines recommend starting at age 20.

You should have a cholesterol test done at an earlier age if you have:

• Diabetes
• Heart disease
• Stroke
• High blood pressure
• A strong family history of heart disease

Follow-up testing should be done:

• Every 5 years if your results were normal.
• More often for people with diabetes, high blood pressure, heart disease, stroke, or blood flow problems to the legs or feet.
• Every year or so if you are taking medicines to control high cholesterol.

The ideal values for all cholesterol results depend on whether you have heart disease, diabetes, or other risk factors. Your healthcare provider can tell you what your goal should be.

Adults

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, beginning at age 18. It is frequently done in conjunction with a routine physical exam.

More-frequent cholesterol testing (often several times per year) might be needed if your initial test results were abnormal or if you already have coronary artery disease, you’re taking cholesterol-lowering medications, or you’re at higher risk of coronary artery disease. Major risk factors include:

• Cigarette smoking
• Being overweight or obese
• Having an unhealthy diet
• Being physically inactive (not getting enough exercise)
• Age (men 45 years or older or women 55 years or older)
• Having high blood pressure (hypertension) or taking high blood pressure medications
• Family history of premature heart disease (heart disease in an immediate family member—male relative under age 55 or female relative under age 65)
• Having pre-existing heart disease or already having had a heart attack
• Having diabetes or prediabetes
• Have a family history of high cholesterol or heart attacks.

People with a history of heart attacks or strokes require regular cholesterol testing to monitor the effectiveness of their treatments.

Children and young adults

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.

Monitoring

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 and the American Heart Association 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.

How to test cholesterol

Some cholesterol is considered good and some is considered bad. Different blood tests can be done to measure each type of cholesterol.

Your doctor may order only a total cholesterol level as the first test. It measures all types of cholesterol in your blood.

A complete cholesterol test includes the calculation of four types of fats (lipids) in your blood:

• Total cholesterol. This is a sum of your blood’s cholesterol content.
• High-density lipoprotein (HDL) cholesterol. This is called the “good” cholesterol because it helps carry away LDL cholesterol, thus keeping arteries open and your blood flowing more freely.
• Low-density lipoprotein (LDL) cholesterol. This is called the “bad” cholesterol. Too much of it in your blood causes the buildup of fatty deposits (plaques) in your arteries (atherosclerosis), which reduces blood flow. These plaques sometimes rupture and can lead to a heart attack or stroke.
• Triglycerides. Triglycerides are a type of fat in the blood. When you eat, your body converts calories it doesn’t need into triglycerides, which are stored in fat cells. High triglyceride levels are associated with several factors, including being overweight, eating too many sweets or drinking too much alcohol, smoking, being sedentary, or having diabetes with elevated blood sugar levels.

Some other information may be reported as part of the lipid panel. These parameters are calculated from the results of the tests identified above.

• Very low-density lipoprotein cholesterol (VLDL-C) — calculated from triglycerides/5; this formula is based on the typical composition of VLDL particles.
• Non-HDL-cholesterol (non-HDL-C) is calculated from total cholesterol minus HDL-C.
• Cholesterol/HDL ratio — calculated ratio of total cholesterol to HDL-C.

An extended profile (or advanced lipid testing) may also include low-density lipoprotein particle number/concentration (LDL-P). This test measures the number of LDL particles, rather than measuring the amount of LDL-cholesterol. It is thought that this value may more accurately reflect heart disease risk in certain people.

Lipoproteins are made of fat and protein. They carry cholesterol, triglycerides, and other fats, called lipids, in the blood to various parts of the body.

How you prepare for cholesterol test

Generally you’re required to fast, consuming no food or liquids other than water, for nine to 12 hours before the cholesterol test. Some cholesterol tests don’t require fasting, so follow your doctor’s instructions.

The cholesterol test procedure

A cholesterol test is a blood test, usually done in the morning since you’ll need to fast for the most accurate results. Blood is drawn from a vein, usually from your arm.

Before the needle is inserted, the puncture site is cleaned with antiseptic and an elastic band is wrapped around your upper arm. This causes the veins in your arm to fill with blood.

After the needle is inserted, a small amount of blood is collected into a vial or syringe. The band is then removed to restore circulation, and blood continues to flow into the vial. Once enough blood is collected, the needle is removed and the puncture site is covered with a bandage.

The procedure will likely take a couple of minutes. It’s relatively painless.

There are no precautions you need to take after your cholesterol test. You should be able to drive yourself home and do all your normal activities. You might want to bring a snack to eat after your cholesterol test is done, if you’ve been fasting.

What do the results of a cholesterol test mean?

In the United States, cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood. In Canada and many European countries, cholesterol levels are measured in millimoles per liter (mmol/L).

If your results show that your cholesterol level is high, don’t get discouraged. You might be able to lower your cholesterol with lifestyle changes, such as quitting smoking, exercising and eating a healthy diet.

If lifestyle changes aren’t enough, cholesterol-lowering medications also might help. Talk to your doctor about the best way for you to lower your cholesterol.

Normal total cholesterol

A total cholesterol of 180 to 200 mg/dL (10 to 11.1 mmol/l) or less is considered best.

You may not need more cholesterol tests if your cholesterol is in this normal range.

Abnormal cholesterol test results

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 American College of Cardiology and the American Heart Association published new guidelines on treatment of cholesterol to reduce cardiovascular disease risk in adults. These guidelines recommend a treatment strategy different than those from National Cholesterol Education Program (NCEP). Decisions about cholesterol-lowering therapies are no longer focused on LDL-C or non-HDL-C targets, but are based on the 10-year risk of atherosclerotic cardiovascular disease and other factors.

The latest guidelines include a newly developed, evidence-based risk calculator for atherosclerotic cardiovascular disease used to identify individuals most likely to benefit from therapy. It is intended for people without heart disease between the ages of 40 and 79. Many factors are considered in the calculation, including age, gender, race, total cholesterol, HDL-C, blood pressure, presence of diabetes, and smoking habit. Additionally, the updated guidelines recommend evaluating therapeutic response compared to LDL-C baseline values, with reduction thresholds differing based on the intensity of the lipid-lowering drug therapy.

However, use of the updated guidelines remains controversial. Many still use the older guidelines from the National Cholesterol Education Program ATP III to evaluate lipid levels and cardiovascular disease (CVD) risk:

Table 1. To interpret your test results, use these general guidelines.

Footnote: *Canadian and European guidelines differ slightly from U.S. guidelines. These conversions are based on U.S. guidelines.

Adults

In general, healthy lipid levels help to maintain a healthy heart and lower the risk of heart attack or stroke. A health practitioner will take into consideration the results of each component of a lipid panel plus other risk factors to help determine a person’s overall risk of coronary heart disease, whether treatment is necessary and, if so, which treatment will best help to lower the person’s risk of heart disease.

Total Cholesterol

For adults, in a routine setting where Total Cholesterol testing is done to screen for risk, the Total Cholesterol test results are grouped in three categories of risk:

1. Desirable: A cholesterol below 200 mg/dL (5.18 mmol/L) is considered desirable and reflects a low risk of heart disease.
2. Borderline high: A cholesterol of 200 to 239 mg/dL (5.18 to 6.18 mmol/L) is considered to reflect moderate risk. If the cholesterol test was done by itself, a healthcare practitioner may decide to order a lipid profile to see if the high cholesterol is due to the amount of bad cholesterol (high LDL-C) or good cholesterol (high HDL-C). Depending on the results of the lipid profile (and any other risk factors), a decision will be made about whether treatment, including lifestyle changes, is necessary.
3. High risk: A cholesterol greater than or equal to 240 mg/dL (6.22 mmol/L) is considered high risk. A health care provider may order a lipid profile (as well as other tests) to try to determine the cause of the high cholesterol. Once the cause is known, an appropriate treatment will be prescribed.

LDL Cholesterol

• Optimal: Less than 100 mg/dL (2.59 mmol/L); for those with known disease (atherosclerotic cardiovascular disease or diabetes), less than 70 mg/dL (1.81 mmol/L) is optimal
• Near/above optimal: 100-129 mg/dL (2.59-3.34 mmol/L)
• Borderline high: 130-159 mg/dL (3.37-4.12 mmol/L)
• High: 160-189 mg/dL (4.15-4.90 mmol/L)
• Very high: Greater than 190 mg/dL (4.90 mmol/L)

HDL Cholesterol

• Low level, increased risk: Less than 40 mg/dL (1.0 mmol/L) for men and less than 50 mg/dL (1.3 mmol/L) for women
• Average level, average risk: 40-50 mg/dL (1.0-1.3 mmol/L) for men and between 50-59 mg/dl (1.3-1.5 mmol/L) for women
• High level, less than average risk: 60 mg/dL (1.55 mmol/L) or higher for both men and women

Fasting Triglycerides

• Desirable: Less than 150 mg/dL (1.70 mmol/L)
• Borderline high: 150-199 mg/dL(1.7-2.2 mmol/L)
• High: 200-499 mg/dL (2.3-5.6 mmol/L)
• Very high: Greater than 500 mg/dL (5.6 mmol/L)

Non-HDL Cholesterol

• Optimal: Less than 130 mg/dL (3.37 mmol/L)
• Near/above optimal: 130-159 mg/dL (3.37-4.12mmol/L)
• Borderline high: 160-189 mg/dL (4.15-4.90 mmol/L)
• High: 190-219 mg/dL (4.9-5.7 mmol/L)
• Very high: Greater than 220 mg/dL (5.7 mmol/L)

Unhealthy lipid levels and/or the presence of other risk factors such as age, family history, cigarette smoking, diabetes and high blood pressure, may mean that the person tested requires treatment.

The National Cholesterol Education Program (NCEP) Adult Treatment Panel III guidelines uses the results of lipid tests and these other major risk factors to define target LDL cholesterol levels. According to those guidelines, if individuals have LDL-C above the target values, they will be treated.

The target LDL-C value is:

• Less than 100 mg/dL (2.59 mmol/L) if the person has heart disease or diabetes [and ideally less than 70 mg/dL (1.81 mmol/L)]
• Less than 130 mg/dL (3.37 mmol/L) if the person has 2 or more risk factors
• Less than 160 mg/dL (4.14 mmol/L) if the person has 0 or 1 risk factor

For children and adolescents

A full, fasting lipid panel is recommended for screening youths with risk factors for developing heart disease, according to the American Academy of Pediatrics. Fasting prior to lipid screening in children without risk factors is unnecessary. Non-high-density lipoprotein cholesterol (non-HDL-C) is the recommended test for non-fasting lipid screening. Non-HDL-C-is calculated by testing for total cholesterol and HDL-C and taking the difference between the two levels. Recommended cut-off values include:

For children and adolescents:

Total Cholesterol

1. A cholesterol below 170 mg/dL (4.40 mmol/L) is acceptable.
2. A result of 170-199 mg/dL (4.40-5.16 mmol/L) is borderline.
3. A total cholesterol reading greater than or equal to 200 mg/dL (5.17 mmol/L) is considered high.

Non-HDL Cholesterol

1. Non-HDL Cholesterol below 120 mg/dL (3.10 mmol/L) is acceptable.
2. A result of 120-144 mg/dL (3.10-3.72 mmol/L) is borderline.
3. Non-HDL Cholesterol greater than or equal to 145 mg/dL (3.75 mmol/L) is considered high.

For young adults:

Total Cholesterol

1. A cholesterol below 190 mg/dL (4.92 mmol/L) is acceptable.
2. A result of 190-224 mg/dL (4.92-5.80 mmol/L) is borderline.
3. A total cholesterol greater than or equal to 225 mg/dL (5.82 mmol/L) is considered high.

Non-HDL Cholesterol

1. Non-HDL Cholesterol below 150 mg/dL (3.88 mmol/L) is acceptable.
2. A result of 150-189 mg/dL (3.88-4.89 mmol/L) is borderline.
3. Non-HDL Cholesterol greater than or equal to 190 mg/dL (4.91 mmol/L) is considered high.

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.

1. Cholesterol Home Use Tests. https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/InVitroDiagnostics/HomeUseTests/ucm125686.htm[↩]