Blood-tests Explained


Disclaimer:

This website is intended to assist with patient education and should not be used as a diagnostic, treatment or prescription service, forum or platform. Always consult your own healthcare practitioner for a more personalised and detailed opinion

Lp(a)


At a Glance

Why Get Tested?

To give your health practitioner additional information about your risk of developing heart disease; as part of a targeted screen for cardiovascular disease (CVD)

When to Get Tested?

When you have a family history of CVD at a young age; when you have heart disease or have had a heart attack or stroke but your lipid profile is normal or shows only mildly elevated cholesterol and/or low-density lipoprotein cholesterol (LDL-C)

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None; however, Lp(a) is often performed at the same time as a lipid profile and fasting for 9-12 hours may be required for the lipid profile.

The Test Sample

What is being tested?

Lipoprotein (a) or Lp(a) is one type of lipoprotein that carries cholesterol in the blood. It is similar to low-density lipoprotein (LDL, the "bad" cholesterol) in that it contains a single apolipoprotein B protein along with cholesterol and other lipids. This test measures the amount of Lp(a) in the blood to help evaluate a person's risk of developing cardiovascular disease (CVD).

Like LDL, Lp(a) is considered a risk factor for CVD. The amount of Lp(a) that a person has is genetically determined and remains relatively constant over an individual's lifetime. A high level of Lp(a) is thought to contribute to a person's overall risk of CVD, making this test potentially useful as a cardiovascular risk marker.

The protein portion of Lp(a) consists of:

  • Apolipoprotein B (Apo B) – a protein that is involved in the metabolism of lipids and is the main protein constituent of lipoproteins such as LDL and very low-density lipoprotein (VLDL)
  • Apolipoprotein(a) – A second protein component, called apolipoprotein(a), which is attached to the Apo B. Apolipoprotein(a) has an unusual structure and is thought to inhibit clots from being broken down normally. The size of the apolipoprotein(a) portion of Lp(a) varies in size from person to person and tends to be smaller in Caucasians than in those of African ancestry. The significance of the variation in size in contributing to CVD risk is complex, but there is some evidence that smaller size increases risk. Most Lp(a) tests do not measure the size of apolipoprotein(a), however. They measure and report only the level of Lp(a) in blood.

Since about 50% of the people who have heart attacks have a normal cholesterol level, researchers have soughtother factors that may have an influence on heart disease. It is thought that Lp(a) may be one such factor. Lp(a) has two potential ways to contribute. First, since Lp(a) can promote the uptake of LDL into blood vessel walls, it may promote the development of atherosclerotic plaque on the walls of bloodvessels. Secondly, since apo(a) has a structure that can inhibit enzymes that dissolve clots, Lp(a) may promote accumulation of clots in the arteries. For these reasons, Lp(a) may be more atherogenic than LDL.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

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 lipid profile, fasting for 9-12 hours may be required.

The Test