Lipoprotein(a), Lp(a): an inherited cholesterol risk factor

Lp(a) is a lipoprotein consisting of a lipid-rich core surrounded by two proteins, apolipoprotein B100 and apolipoprotein(a). It resembles LDL but with the extra apolipoprotein(a) attached. Lab Tests Online UK explains that it may accelerate atherosclerotic damage by increasing the size of plaque in artery walls, that it is retained in the artery wall more than LDL cholesterol because apolipoprotein(a) binds to the artery lining, and that it is thought to interfere with clotting mechanisms, promoting clot development on the inner surface of blood vessels.

This dual action, building plaque and favouring clots, may explain its role in promoting cardiovascular disease.

Lp(a) is not part of the routine health check. A doctor may request it if you have a family history of premature cardiovascular disease or of elevated Lp(a), or developed cardiovascular disease at a young age, particularly without conventional risk factors such as high total or LDL cholesterol. The European Atherosclerosis Society, per Lab Tests Online UK, recommends that people at intermediate, moderate or high cardiovascular risk should have it measured, including those with premature cardiovascular disease, familial hypercholesterolaemia, a family history of premature disease or elevated Lp(a), and recurrent disease despite optimum treatment.

The result helps doctors judge how much Lp(a) contributes to your risk, which matters for how firmly other risks should be treated.

A blood sample is taken from a vein in the arm with no special preparation. Because the level is stable, a single measurement is usually enough. Lp(a) is slightly lower in men than in women and increases a little in women after the menopause, and it varies with ethnicity: Lab Tests Online UK says people of African American descent can have concentrations up to four times higher than Caucasians, though without necessarily higher coronary risk.

High Lp(a) concentrations increase the risk of coronary artery disease and cerebrovascular disease, especially in people with hypercholesterolaemia. The figure itself is only one input: a high level in someone with otherwise excellent risk factors carries different weight from a high level in someone with diabetes or very high LDL cholesterol. Laboratories report the level in different units and use different reference limits, so rely on your own report and your doctor's advice rather than comparing numbers from other sources.

Lp(a) is often a reason to ask about relatives. Because it is inherited, close family members may wish to be tested, and doctors may also consider familial hypercholesterolaemia if LDL cholesterol is high.

Current advice is to treat the other modifiable risk factors of coronary artery disease maximally, especially LDL cholesterol, and to add aspirin if there are no contraindications. The NHS says statins are the most common medicine for high cholesterol and other options include ezetimibe, bempedoic acid and injections such as alirocumab, evolocumab and inclisiran. Aspirin is a prescribing decision: do not start it on your own, especially if you have bleeding risks.

Several new medicines that may affect Lp(a) are in development, according to Lab Tests Online UK; none is described there as established treatment.

Keep blood pressure, glucose, weight, smoking and LDL cholesterol under tight control and attend regular cardiovascular reviews. Know the warning signs: chest pain, breathlessness, or sudden weakness, speech or vision change need an immediate 999 call.