At a Glance
Why Get Tested?
To help determine your risk of developing heart disease and to monitor lipid-lowering lifestyle changes and drug therapies; to accurately determine your low-density lipoprotein cholesterol (LDL-C) concentration when you have raised triglyceride concentrations
When to Get Tested?
A blood sample taken from a vein in your arm
Test Preparation Needed?
No test preparation is needed. Your doctor might recommend that you fast (water only) for 14 hours prior to the test so that other related substances can be measured in the same sample.
The Test Sample
What is being tested?
The direct low-density lipoprotein cholesterol test (direct LDL-C) measures the amount of LDL cholesterol, sometimes called “bad” cholesterol, in the blood. Elevated concentrations are associated with increased risk of atherosclerosis and heart disease. Usually, the amount of LDL cholesterol (LDL-C) is calculated using the results of a standard lipid profile. In most cases, this is a good estimate of the LDL-C, but it becomes less accurate with increased triglyceride concentrations (greater than 4 mmol/L) Direct measurement of LDL-C is less affected by triglycerides and can be used when you are not fasting or when you have significantly elevated triglycerides.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed. Your doctor might recommend that you fast (water only) for 14 hours prior to the test, so that other related substances can be measured in the same sample.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.