Lipoprotein (a)

Why get tested?
To give your doctor additional information about your risk of developing heart disease; as part of targeted screening for coronary artery disease (CAD) and cerebrovascular disease (CVD)

When to get tested?
When you have a family history of high Lp(a) levels and/or of premature CAD; when you have heart disease but your lipid profile is normal or shows only slightly raised cholesterol and/or low-density lipoprotein cholesterol (LDL-C).

Sample required?

A blood sample from a vein in the arm

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
Lp(a) may be requested together with other lipid tests as selective screening for risk factors for coronary artery disease and cerebrovascular disease. Some doctors are starting to request Lp(a) and several other emerging cardiac risk markers (such as Apo B, hs-CRP, Apo A and homocysteine levels) for patients with a family history of premature coronary artery disease.

Some doctors may also request these tests for patients with heart or vascular disease, particularly those whose lipid levels are normal or slightly raised. Since about 50% of people who have heart attacks have normal cholesterol levels, doctors have started to look at other factors that may influence heart disease. High Lp(a) levels are thought to aggravate other processes of heart and vascular disease.

When is it requested?
Lp(a) may be requested, together with other lipid tests, when there is a family history of premature coronary artery disease and when the doctor suspects familial hypercholesterolaemia. The doctor may also request Lp(a) when a person has had a stroke or heart attack, even if their lipid levels are normal or only slightly raised.

In rare cases Lp(a) may be requested for a post-menopausal woman to see whether the rise in Lp(a) (linked to falling oestrogen levels) has significantly increased her risk of developing CAD.

What does the test result mean?
Lp(a) levels are genetically determined and remain relatively constant throughout a person’s life. They are not affected by lifestyle changes or by most medicines.

High Lp(a) levels increase a person’s risk of developing coronary artery disease and cerebrovascular disease and can occur even in patients with a normal lipid profile. High Lp(a) levels are thought to act independently in the processes linked to heart or vascular disease. Other conditions that can cause high Lp(a) levels include:

• Chronic kidney failure
• Oestrogen depletion
• Familial hypercholesterolaemia
• Myocardial infarction (heart attack)
• Premature coronary artery disease
• Severe hypothyroidism
• Narrowing of the cerebral arteries
• Stroke
• Uncontrolled diabetes

Low Lp(a) levels do not appear to cause problems. They seem to be linked to:

• Alcoholism
• Chronic liver disease
• Malnutrition

Is there anything else I should know?
Although some cardiologists and other doctors are starting to request Lp(a), this test is not yet requested routinely. A recent National Institutes of Health (NIH) guideline, the “Adult Treatment Panel III” (p. II-21, available as a PDF), recognised the possible usefulness of Lp(a) and other emerging cardiac risk tests, but does not recommend them for widespread screening.
This is partly because Lp(a) levels are genetically determined and hard to change. Small amounts of nicotinic acid and oestrogens (for post-menopausal women) have been seen to lower Lp(a) levels, but their effect seems to be short-term, and it is not known whether lowering Lp(a) actually lowers the level of risk. At present experts do not recommend medicines for high Lp(a) levels, but some suggest that patients with high Lp(a) should be particularly careful to lower their low-density lipoprotein (LDL, the “bad” cholesterol) levels, and so help lower their overall risk.

In general, lipids should not be measured during a fever or serious infection, within four weeks of an acute myocardial infarction (heart attack), stroke or surgery, after heavy drinking, with severe uncontrolled diabetes, during pregnancy or during rapid weight loss.