What is HDL cholesterol?
The abbreviation HDL means "high-density lipoprotein", it is one of the classes of lipoproteins carrying cholesterol in the blood.
HDL cholesterol is mainly made up of protein with a small amount of cholesterol. It is considered benign because it removes surplus cholesterol from tissues and transports it to the liver, where it is broken down. This is why HDL cholesterol is often referred to as the "good" cholesterol.
High levels of other types of cholesterol have proven to be associated with the development of hardening of the arteries and heart disease.
This means, when other types of “bad” cholesterol levels in the blood increase (i.e. insufficient amounts are removed by the HDL cholesterol), it may be deposited on the walls of the blood vessels.
These deposits, also known as plaque, may build up and cause the walls of the vessels to become rigid. They can gradually restrict the openings in blood vessels, slowing the flow of blood.
A higher level of blood HDL cholesterol is good as it can reduce the risk of developing plaque by removing the other cholesterol types from the blood. This can help reduce the risk of heart attack or stroke.
Why do we need to analyse HDL cholesterol?
The HDL cholesterol test is usually carried out together with other lipid tests including total cholesterol, LDL cholesterol and triglycerides as part of a lipid profile during a health check.
This is done to help identify unhealthy levels of lipids and calculate the risk of developing cardiovascular disease.
HDL cholesterol should be monitored regularly if:
- previous test results have indicated an increased risk of cardiovascular disease
- if someone in your family has had a heart attack
- if someone in your family is undergoing treatment for high cholesterol
If you are in the low risk group, it is recommended that all adults should be tested at least once every five years.
Major risk factors include:
- Smoking cigarettes
- Age (men aged 45 and over or women aged 55 and over)
- Hypertension (blood pressure of 140/90 or higher, or people taking medication for high blood pressure)
- Family history of early heart disease (heart disease in a close relative)
- Existing heart disease or previous heart attack
HDL cholesterol levels can also be investigated at regular intervals in order to evaluate the success of lifestyle changes – changing your diet or exercise regime or giving up smoking, for example – with a view to increasing your HDL cholesterol level.
High levels of HDL cholesterol
High HDL cholesterol levels often mean a decreased risk of cardiovascular disease. High HDL cholesterol levels may also be due to:
- Hereditary factors
- The effect of oestrogen
- High levels of physical activity
- Alcohol consumption
Low levels of HDL cholesterol
Low levels may be due to:
- Inflammatory processes, in particular viral hepatitis
- Hereditary factors (Tangier disease, LCAT deficiency)