Lp(a)

Also known as: Lipoprotein little a

Formal name: Lipoprotein (a)

Related tests: Lipid Profile, Homocysteine, hs-CRP, Apo A, Apo B

The Test Sample

What is being tested?

Lp(a) may be an independent risk factor for heart disease; i.e., patients with acceptable lipid levels but elevated Lp(a) are still at risk for heart disease. It is a lipoprotein, consisting of an LDL molecule attached to another protein, Apolipoprotein (a). In the body, Apolipoprotein (a) can interfere with the function of plasminogen (resulting in blood clot formation) and can help bind LDL molecules to artery walls (speeding up plaque formation and the narrowing and hardening of the arteries). It is this dual action that may explain the role of Lp(a) in the promotion of cardiovascular disease.

Lp(a) levels are genetically determined and will remain fairly constant in an individual over a lifetime; their levels are not affected by diet, exercise, and other typical lifestyle modifications used to lower lipid levels. They can rise a bit higher in post menopausal women. Lp(a) levels also vary by ethnicity; those patients of African American descent tend to have levels 3 to 4 times higher than Caucasians but, for reasons that are not well understood yet, they do not have a higher risk for CAD.

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; however, since this test may be performed at the same time as a complete lipid profile, fasting for at least 12 hours may be required.