About the Test
Purpose of the test
LDL cholesterol testing measures the amount of LDL cholesterol in your blood. Because LDL levels can provide information about cardiovascular health, they may be measured as part of diagnosis, screening, or monitoring.
- Diagnosis: An LDL cholesterol test may be used to diagnose high cholesterol in your blood.
- Screening: Screening means testing LDL cholesterol levels before any symptoms occur. Because health issues can occur when cholesterol levels are too high, doctors may check your LDL cholesterol levels to get a baseline measurement. Your doctor can compare future measurements to this one to get an idea of your cholesterol trends.
- Monitoring: Monitoring your cholesterol levels at regular intervals over time enables doctors to notice any changes and to see if treatment for conditions, like heart disease or high cholesterol, are working.
What does the test measure?
An LDL cholesterol test checks the amount of LDL cholesterol in the blood. Results are typically measured in milligrams per deciliter (mg/dL).
Cholesterol is a fatty substance your body naturally creates to help in digesting food, creating hormones, and cell membranes. The substance is made up of different types of lipoproteins, which are a combination of fats, also known as lipids, and proteins. Lipids connect to proteins to be able to move through your blood. Cholesterol testing often measures different substances in the blood:
- High-density (HDL) cholesterol: This carries cholesterol from other parts of your body to your liver for processing and removal and is considered the “good” cholesterol.
- LDL cholesterol: This is known as the “bad” cholesterol because too much of it in your blood can lead to a buildup of plaque in your arteries, putting you at risk of heart disease, diabetes, or stroke.
- Triglycerides: These are fats created by the foods we eat, stored until your body needs energy. Triglycerides are processed by your body when it needs energy. Having high levels of triglycerides can lead to coronary heart disease and other cardiovascular issues.
- Very low-density (VLDL) cholesterol: VLDL is similar to LDL cholesterol but carries triglycerides through the blood. VLDL can contribute to plaque buildup and is considered a “bad” cholesterol.
Knowing about these different components of cholesterol testing is important to understanding the options for checking your LDL level. These levels can be estimated based on the number of other types of cholesterol in the blood or can be measured directly:
- Calculated LDL cholesterol testing: In this test, total cholesterol, HDL cholesterol, and triglycerides are used to estimate LDL cholesterol levels in your blood. Usually, LDL is calculated by subtracting the amount of HDL and VLDL from the total amount of cholesterol. In most cases, LDL cholesterol levels reported by your doctor are calculated rather than measured directly.
- Direct LDL cholesterol testing: Tests that measure only LDL cholesterol levels in your blood are called direct LDL cholesterol tests. Your doctor might use a direct LDL cholesterol test if you have a high level of triglycerides, which can make the formula-based calculation of LDL less accurate.
Most of the time, using a formula to calculate LDL cholesterol is accurate enough to provide your doctor with a useful assessment of your cholesterol levels.
When should I get an LDL cholesterol test?
LDL cholesterol testing may be used to assess your risk of cardiovascular disease or monitor changes in cholesterol over time.
Doctors will take factors such as age, family history, and other medical conditions when determining how often you should check your levels of LDL cholesterol. Examples of common screening recommendations are outlined below:
| DEMOGRAPHIC GROUP | RISK FACTORS | SCREENING FREQUENCY |
|---|---|---|
| Children | No risk factors | Once between ages 9-11; again between 17-21 years old |
| Children | One or more | Every 1-3 years starting when the risk factor is identified |
| Adolescents and adults of any age | One or more | At least every 5 years; often more frequently based on specific risk factors |
| Males ages 20-45 years
Females ages 20-55 years |
No risk factors | Every 4-6 years |
| Males ages 45-65 years
Females ages 55-65 years |
No risk factors | Every 1-2 years |
| People over 65 years | With or without risk factors | Annually |
Having your cholesterol levels checked at regular intervals gives doctors a chance to notice any changes that could become harmful to your health. High or increasing cholesterol levels are a risk factor for heart disease, diabetes, or stroke, among other conditions.
Doctors may want to test your cholesterol levels more regularly if you or your family have a history of heart disease, smoking, high blood pressure, type 2 diabetes, obesity, a sedentary lifestyle, or a diet high in saturated fat.
Finding an LDL Cholesterol Test
How can I get an LDL Cholesterol test?
Doctors may order a cholesterol test to check your levels, which are measured in your blood. Blood samples are typically collected in a doctor’s office, hospital, or another medical facility. Once a sample of blood is collected, it is sent to a laboratory for testing.
You can also order an LDL test online as part of a Lipid Panel and give your sample at a local lab.
Can I take the test at home?
At-home cholesterol testing is available to measure calculated levels of LDL cholesterol. Testing for cholesterol at home uses a blood sample taken by a device that pricks your finger to obtain a small drop of blood that can be tested.
There are two types of at-home LDL tests that use a fingerstick blood sample:
- Self-tests: In this kind of test, the analysis of your blood happens at home. This can be done by applying a drop of blood on paper that is then placed into a small device that determines the cholesterol levels. Another type of self-test uses chemically treated paper that indicates the levels of cholesterol in your blood.
- Self-collection: For this kind of test, your blood sample is taken at home but is then sent to a laboratory for analysis.
For help deciding whether an at-home cholesterol test kit is right for you, it may be helpful to talk to your primary care doctor or cardiologist. It is common to have a follow-up cholesterol test performed by a doctor if an at-home cholesterol test kit finds abnormal results.
How much does the test cost?
You may find it helpful to talk with your doctor about the costs of cholesterol testing. The price may depend on the type of cholesterol test, your insurance coverage, and where the test is performed.
Blood testing is typically covered by insurance when prescribed by a doctor, but you may be responsible for out-of-pocket costs on copays, deductibles, or technician fees.
Taking an LDL Cholesterol Test
Cholesterol testing, including a lipid panel, is performed using a blood sample. Blood is most often taken from a vein in your arm. The blood sample is then analyzed in a laboratory.
Before the test
When cholesterol tests are performed in a doctor’s office or another health care facility, the doctor may ask you not to eat for the eight to 12 hours leading up to testing. This is known as fasting. Cholesterol testing is often performed in the morning to make it easier for you to fast while you sleep. Usually, drinking water is allowed before your cholesterol test. Your doctor will give you any instructions you need to follow prior to having your cholesterol tested.
During the test
During a cholesterol test performed in a lab or medical facility, a sample of blood is taken from a vein in your arm using a needle. Before blood is drawn, you may have an elastic band tied around your upper arm, which forces your veins to swell with blood and makes it easier for the person administering the test to find a vein.
Once a vein has been located, the site will be disinfected with antiseptic, a germ-killing substance. When the needle has been inserted, blood will flow through the needle into an attached test tube or vial to be sent to a lab for analysis. You may experience a temporary stinging sensation when the needle is inserted.
After the test
After the blood has been drawn for a laboratory-based lipid panel, the needle will be removed from your arm. The injection site may be wiped or covered with a bandage if any bleeding occurs.
Blood testing presents very little risk to your health. You may experience slight bruising or tenderness at the injection site, but these effects usually go away quickly.
LDL Cholesterol Test Results
Receiving test results
When a blood test is performed at a health care facility as part of a lipid panel or direct LDL measurement, results are usually sent back from the lab within a few days. Your doctor may share your results with you through an online health portal or in the mail. They may want to schedule a follow-up visit to discuss your results or potential next steps.
Interpreting test results
LDL cholesterol levels are most commonly measured in mg/dL. Because high levels of LDL can indicate a greater risk of heart disease and stroke, a low amount of LDL cholesterol is preferred. LDL cholesterol levels are categorized into the following segments:
| LDL CHOLESTEROL LEVEL | LDL CHOLESTEROL CATEGORY |
|---|---|
| Less than 100 mg/dL | Optimal |
| 100-129 mg/dL | Near optimal |
| 130-159 mg/dL | Borderline high |
| 160-189 mg/dL | High |
| 190 mg/dL and above | Very high |
LDL levels are not interpreted alone but rather as part of your overall health. Accordingly, LDL cholesterol results ranging between 70 mg/dL and 189 mg/dL can be considered too high if you have diabetes, heart disease, a history of a stroke, poor circulation to your legs, or other conditions.
Your doctor can best help you understand what your specific test results mean for your health. Some doctors may set a specific target level when prescribing medication to lower cholesterol. Factors like diet, age, smoking, physical activity, weight, sex, genetics, medicines, and other medical conditions can all affect your LDL cholesterol level.
Continued cholesterol monitoring, increased physical activity, changed dietary habits, and medication may all be recommended to lower LDL cholesterol levels. Reducing LDL cholesterol may help decrease your risk of heart disease, stroke, or other cardiovascular conditions.
Cholesterol testing is done at regular intervals to track changes in your cholesterol levels over time. Repeat testing at regular intervals will be necessary if you have high LDL cholesterol levels, risk factors for heart disease or diabetes, or if you’re being treated for high cholesterol.
If you have had a calculated LDL cholesterol test that found high triglyceride levels, doctors may order a direct LDL cholesterol test.
After taking a test, you may wish to discuss the results with your physician. Here are some questions you can ask:
- What are my LDL cholesterol levels?
- Do you consider my LDL level to be too high?
- What should my LDL cholesterol level be?
- How can I lower my LDL cholesterol level?
- Will I need a prescription to lower my cholesterol?
- How often will we check my cholesterol levels?
