Making sense of Lp(a)
Making sense of Lp(a)
Lipoprotein(a) (Lp(a)) is a particle made by the liver, which carries cholesterol, fats and proteins in the blood. It is sometimes known as ‘lipoprotein little a’ or ‘Lp little a’.
Most people have some Lp(a) in their body but about 1 in 5 people have high levels of this protein due to a specific gene in their DNA. Most people are unaware if they have elevated Lp(a).
People living with high levels of Lp(a) have a 2-4 times higher risk of developing early heart disease, heart attacks and strokes than those with lower Lp(a) levels.
The amount of Lp(a) a person’s body makes is determined by the genes passed down from their parents. People cannot change the amount of Lp(a) they have in their body by changing their diet or making other lifestyle changes, unlike other lipid (fat) levels. By the time a child is 5 years old, their Lp(a) levels will be at the level they will likely remain for the rest of their lives.
Having raised levels of Lp(a) generally causes no symptoms until a person develops cardiovascular disease, and most people are not aware that they are affected. The only way to detect high Lp(a) is to have a blood test, but currently, most standard cholesterol tests do not screen for Lp(a).
Current medicines that are used to lower lipid levels in the blood do not have a meaningful effect on Lp(a), and are less effective overall in people with high levels of Lp(a). However, it is important to manage other modifiable risk factors for heart disease and stroke in order to reduce the overall risk of cardiovascular disease. These include high blood pressure or cholesterol, raised blood sugar levels, smoking, obesity and lack of physical activity.
A number of potential new treatment options are currently in development. One area under investigation is called ‘gene silencing therapy’, which is designed to temporarily block a specific gene’s message that would otherwise trigger an unwanted effect. This has the potential to reduce levels of Lp(a) and thereby reduce the risk of cardiovascular disease.
+What are lipoproteins?
Cholesterol is a fatty substance that is required in small quantities for good health. It is produced in the liver and is also present in some foods. Cholesterol is transported around the body by lipoproteins, which are parcels of protein and fats.
There are different types of lipoprotein. The two most commonly known are high-density lipoprotein (HDL), sometimes referred to as ‘good cholesterol’ and low-density lipoprotein (LDL), also known as ‘bad cholesterol’. Having too much LDL cholesterol can clog up the arteries, which can lead to a heart attack or stroke.
Lp(a) is a specific type of LDL. Its exact function is not known, but it is thought to play a role in healing wounds in the body. High levels of Lp(a) are strongly associated with heart disease and stroke.
+ How is elevated Lp(a) defined?
Levels of Lp(a) are reported in different units: either mass (mg/dL or mg/L) or, as is now recommended, as particle numbers (nmol/L). [Heart UK]
A ‘normal’ level of Lp(a) is less than 30mg/dL (300mg/L) or less than 75nmol/L.
Elevated Lp(a) is generally defined as levels of 50mg/dl (500mg/L) or 120nmol/L.
+ What effect does elevated Lp(a) have?
Some people produce higher than normal levels of Lp(a).
Lp(a) is a ‘sticky’ protein that has a tendency to build up within blood vessels as it travels through the bloodstream. It starts to collect in the arteries, causing them to narrow (this is called atherosclerosis).
It can also trigger the formation of clots which block the arteries and reduce blood flow to the heart, brain, kidneys and legs. This increases the risk of heart attack, heart failure, peripheral artery disease or stroke.
+How many people are affected by elevated Lp(a)?
Elevated Lp(a) is not rare: it affects 1 in 5 people globally.
It is estimated to affect 63 million people in the US.
High Lp(a) affects all ethnic groups but is more common among African Americans and South Asians.
Levels of Lp(a) may increase in women after the menopause when natural oestrogen levels decline.
+Why do people get elevated Lp(a)?
Lp(a) is an inherited condition. The amount of Lp(a) a person’s body makes is determined by the genes passed down from their parents.
The majority of people with elevated Lp(a) are unaware of the fact and unfortunately, for some people, the first sign of disease is a heart attack or stroke.
+ The genetics of elevated Lp(a)
If a person has elevated Lp(a), their children are more likely to have elevated Lp(a), too.
Many people with elevated Lp(a) are unaware that they are affected and so if there is a family history of cardiovascular disease, or a blood-related family member is diagnosed with elevated Lp(a), it is important to get tested.
+Living with elevated Lp(a): the outlook
People with elevated levels of Lp(a) have a 2-4 times higher risk of early heart and blood vessel disease compared to people with normal Lp(a) levels.
Current treatments have little or no impact on levels of Lp(a) but it is important to manage other modifiable risk factors for cardiovascular disease such as high blood pressure or cholesterol, raised blood sugar and obesity. Lifestyle factors such as giving up smoking, taking regular physical activity, eating a balanced diet and avoiding excess alcohol can also help to reduce the risk of cardiovascular disease.
Living with a diagnosis of elevated Lp(a) can lead to feelings of anxiety and vulnerability. It is important to take steps to support mental health, including speaking to a medical professional.
A number of therapies are currently under development and these may have the potential to reduce levels of Lp(a).