LDL Cholesterol

Cholesterol is a fat-like substance that can be found throughout the body and in the blood. There are different types of cholesterol, and low-density lipoprotein (LDL) cholesterol is sometimes called the “bad” cholesterol because too much of it may clog your arteries with a buildup of plaque.

LDL cholesterol testing assesses how much LDL cholesterol is in your blood. This testing helps inform you and your doctor about your risk of heart disease, stroke, diabetes, and other health conditions. Cholesterol testing can also be used to evaluate whether treatment for high cholesterol is working.

Purpose of the test

Low-density lipoprotein (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 screening, diagnosis, or monitoring.

• 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.
• Diagnosis: An LDL cholesterol test may be used to diagnose high cholesterol in your blood.
• 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 making vitamin D. Cholesterol 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: HDL carries cholesterol from other parts of your body to your liver for processing and removal and is considered the “good” cholesterol.
• Low-density (LDL) cholesterol: LDL 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: Triglycerides are fats created by the foods we eat. These fats are 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. LDL levels can be estimated based on the amount of other types of cholesterol in the blood or can be measured directly:

• Calculated LDL cholesterol testing: In a calculated LDL cholesterol 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 a patient’s doctor are calculated rather than measured directly.
• Direct LDL cholesterol testing: LDL 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. A high triglyceride level can make 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 a useful assessment of your cholesterol levels.

When should I get LDL cholesterol testing?

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:

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.

How to get tested

Doctors may order a cholesterol test to check your cholesterol levels. Cholesterol levels are measured in your blood. Blood samples are typically collected in a doctor’s office, hospital, or other medical facility. Once a sample of blood is collected, it is sent to a laboratory for testing.

Can I take the test at home?

At-home cholesterol testing is available to measure calculated levels of LDL cholesterol. At-home testing for cholesterol 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 cost of cholesterol testing may depend on several factors:

• What type of cholesterol test is being taken
• Whether LDL is being calculated or measured
• Insurance coverage
• Where the test is being 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.

Cholesterol testing, including a direct LDL test or 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 other healthcare facility, the doctor may ask you not to eat for the 8-12 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. Once 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. Some people experience a temporary stinging sensation when the needle is inserted.

After the test

After 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.

Receiving test results

When a blood test is performed at a healthcare 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 milligrams per deciliter (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 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. Lowering LDL cholesterol may help decrease your risk of heart disease, stroke, or other cardiovascular conditions.

Are test results accurate?

While no test is always accurate, measurements of blood cholesterol are an effective tool for estimating your risk of cardiovascular disease. Various factors can affect the accuracy of a cholesterol test:

• Direct vs calculated testing: While calculated LDL cholesterol levels are sufficient in most cases, direct testing provides more accurate results in patients with elevated triglyceride levels. Patients who may have elevated triglyceride levels include those diagnosed with type II diabetes or obesity, patients with a history of considerable alcohol intake, and patients taking medication to increase triglycerides.
• Fasting: In most cases, a lipid profile requires fasting. Eating within 8-12 hours before a lipid panel may increase the level of triglycerides in your bloodstream. Because this increased level of triglycerides could affect the accuracy of calculated LDL cholesterol values, your doctor may request that you refrain from eating prior to your blood draw.

Do I need follow-up tests?

Cholesterol testing is done at regular intervals to track changes to 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, doctor’s may order a direct LDL cholesterol test.

Questions for your doctor about test results

• 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?