Direct Low Density Lipoprotein

Test Quick Guide

Direct LDL cholesterol testing measures the amount of cholesterol found inside low-density lipoproteins (LDL) in a sample of blood. LDL cholesterol is known as a type of “bad” cholesterol because it can build up in the blood vessels such as arteries and increase the risk of stroke, heart disease, and heart attack.

In most lipid panels, LDL cholesterol is estimated using an equation involving other cholesterol measurements. A direct LDL cholesterol test is distinct in that it directly measures LDL cholesterol in the blood.

Direct LDL cholesterol tests can be a tool for early detection of cardiovascular disease risk and may be used for cholesterol monitoring and diagnosis of various health conditions.

About the Test

Purpose of the test

The purpose of a direct LDL cholesterol test is to determine the amount of “bad” LDL cholesterol in the blood. Assessing LDL cholesterol levels can be involved in health screening, monitoring, and diagnosis.

  • Screening is looking for evidence of health problems before any symptoms are present. Evaluating LDL cholesterol levels can play an important role in screening for cardiovascular disease risk. Early detection of high levels of LDL cholesterol can help identify people who are more likely to develop heart disease or experience a heart attack or stroke.
  • Monitoring is checking how a condition progresses over time.LDL cholesterol may be tested periodically to assess cardiovascular health and testing can also be used to see if treatment to lower LDL cholesterol has been effective.
  • Diagnosis is the process of identifying the cause of health problems after symptoms have started. A direct LDL cholesterol test may be part of the diagnostic process for cardiovascular problems. Cholesterol levels may also be tested for certain conditions that affect the pancreas, liver, and thyroid.

What does the test measure?

A direct LDL cholesterol test measures the amount of cholesterol found inside of LDL in a sample of blood.

Cholesterol is a waxy substance that contributes to important cell functions such as cell membrane generation and steroid hormones synthesis. Lipoproteins are particles made of fat and protein that transport cholesterol in the blood, allowing it to move through the body. Although cholesterol is necessary for normal cell activity, having too much cholesterol can have negative health effects.

Cholesterol is categorized into different types by the kind of lipoprotein particle that carries it. LDL cholesterol, which is transported inside LDL particles, is referred to as a “bad” cholesterol because it can accumulate in the arteries and heighten the risk of heart attack, heart disease, and stroke.

When should I get a direct LDL cholesterol test?

Direct measurement of LDL cholesterol is not a routine cholesterol test. Instead, it is most often used if you need a cholesterol test but may have high levels of fat molecules called triglycerides.

High triglycerides can invalidate the formula used to calculate LDL cholesterol. As a result, the doctor may recommend a direct LDL cholesterol test if you had high levels of triglycerides on a prior test or if you have risk factors for high triglycerides.

Conditions associated with high triglycerides levels include:

  • Type 2 diabetes
  • Obesity
  • Use of certain medications
  • Significant alcohol consumption

If you previously had cholesterol testing with a direct LDL cholesterol test, your doctor may recommend that any future screening or monitoring also be done with a direct LDL cholesterol measurement. Keeping the test method consistent makes it easier to compare results of different tests.

Finding a Direct LDL Cholesterol Test

How can I get a direct LDL cholesterol test?

A direct LDL cholesterol test is usually ordered by a doctor and performed with a blood draw in a medical setting like a doctor’s office, laboratory, or hospital. If you have elevated triglycerides that can affect the accuracy of your calculated LDL concentration in a standard lipid panel. You can also order the test online with testing by a Clinical Laboratory Improvement Amendments (CLIA) approved lab.

Can I take the test at home?

Direct LDL cholesterol tests are generally not offered as an at-home test, and few options exist. Some at-home testing kits are available that calculate LDL cholesterol.

How much does the test cost?

Various costs can be associated with a direct LDL cholesterol test. The exact price typically depends on whether you have health insurance and where the testing is performed. As an example, you can buy the test for $44 from Testing.com.

The cost usually includes charges for an office visit, the blood draw procedure, and the laboratory’s analysis. Some or all costs may be paid by insurance if the test is ordered by your doctor. Your insurance provider can clarify any expected out-of-pocket costs such as deductibles and copayments.

If you do not have health insurance, you can talk with your doctor or a hospital administrator about the costs of testing for the uninsured. You can also ask about any programs for reduced-cost services or payment plans.

Taking a Direct LDL Cholesterol Test

A blood sample is required for a direct LDL cholesterol test. Normally, this blood sample will be taken using a needle during a routine blood draw at a clinic, hospital, laboratory, or doctor’s office.

Before the test

Depending on the laboratory’s requirements, you may need to fast before a direct LDL cholesterol test. If fasting is necessary, you have to avoid consuming any food or drinks besides water for eight to 12 hours before your blood draw.

Since pretest instructions can vary, ask your doctor about fasting and any other preparations and then closely follow their directions.

During the test

A direct LDL cholesterol test requires withdrawing a sample of blood from your arm. This is a routine procedure that occurs while you are seated. A phlebotomist or nurse typically ties a band around your upper arm near the bicep, which increases the blood in your veins.

An antiseptic wipe is used to clean the skin close to a vein, and then the nurse or phlebotomist inserts a needle into the vein to collect a vial of blood. Blood is usually taken from a vein on the inside of your elbow.

The entire procedure normally lasts less than a few minutes. You may feel a stinging sensation when the needle is inserted and removed.

After the test

After your blood has been drawn, a bandage may be placed over the puncture site to apply pressure and make sure that any bleeding stops quickly.

If you were told to fast before the test, you can eat once the test is complete. For this reason, you may want to bring a snack to the appointment.

You can generally return to normal activities after blood is withdrawn. Bruising or pain may occur in your arm, but these effects typically go away quickly.

Direct LDL Cholesterol Test Results

Receiving test results

Results from a direct LDL cholesterol test are often available within several business days after your blood draw. The results may be provided to you by your doctor during a phone call or follow-up visit. Results can also be delivered with a test report delivered by mail or through an online health portal.

Interpreting test results

Your direct LDL cholesterol level is normally listed in milligrams per deciliter (mg/dL) of blood, although some labs provide a measurement in millimoles per liter (mmol/L).

In addition to your LDL cholesterol level, the test report will show the reference range used to interpret your test result. The reference range shows LDL cholesterol levels that the lab considers to be normal.

In general, it is desirable to have LDL cholesterol levels below 100 mg/dL.

High levels of LDL cholesterol can lead to a condition called arteriosclerosis. This is an accumulation of plaque in the arteries and can contribute to cardiovascular diseases like coronary heart disease, heart attack, and stroke.

It is important to remember, though, that cholesterol numbers are evaluated within the context of your overall health. Your doctor will also consider your age, sex, family health history, levels of other types of cholesterol, and additional risk factors for cardiovascular disease. Your current LDL cholesterol level may also be compared to your level on prior tests.

A doctor is in the best position to account for these factors, explain the significance of your direct LDL cholesterol test, and discuss whether any treatment is appropriate to modify your risk of cardiovascular disease.

Very low levels of LDL cholesterol are uncommon but can occur with certain health conditions. When low LDL cholesterol is detected, further tests are typically needed to determine its cause.

When you receive the results from a direct LDL cholesterol test, some of these questions may be helpful to bring up with your doctor:

  • What was my measured LDL cholesterol level?
  • Was my LDL cholesterol normal?
  • Do I have other risk factors for cardiovascular disease?
  • Do you recommend any additional tests?
  • Should I take another direct LDL cholesterol test in the future?
  • Do you recommend any treatments to improve my cardiovascular health?

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