High HDL Cholesterol
HDL cholesterol is a type of cholesterol which is essential for good health. It removes fat from the artery walls, lowering the risk of heart disease, but it is possible for it to become too high and lose its protective effects.
How high is too high?
Most health professionals are taught that the higher the HDL cholesterol, the more protective it is for your heart health. However, some specialist doctors are beginning to question this.
Very high levels of HDL have been reported to speed up the process of atherosclerosis, where the arteries become clogged up with fat, suggesting that at very high levels HDL doesn’t do its normal job of clearing fat from the arteries.
Current recommendations for healthy levels of HDL cholesterol
- 1.2mmol/L or above in women
- 1.1mmol/L or above in men
Our HEART UK experts say the protective effect of HDL cholesterol appears to reach its maximum at roughly 1.4mmol/L, and higher levels may not provide extra protection.
Over 2.3mmol/L, HDL may behave more like LDL cholesterol (or ‘bad cholesterol’) and raise the risk of disease, according to current research. This is especially important for women leading up to after the menopause.
What causes high HDL cholesterol?
There are a number of possible causes for high HDL cholesterol, and some of these can be reversed. If you have high HDL cholesterol, your doctor should consider what’s causing it to decide on a course of action.
What you eat and drink
Eating a diet high in saturated fats and drinking too much alcohol can contribute to a higher level of HDL. If you and your doctor discuss making lifestyle changes, you will need to keep these going for an agreed time period, such as three months, before checking your HDL cholesterol levels again to see if the changes are working.
Some medicines could raise your HDL levels, including:
- the oral contraceptive pill (the pill)
- oestrogen replacement therapy
- anti convulsants.
Your doctor should ask you questions about your family to understand if your high HDL could be inherited.
If members of your family, including your parents, grandparents and siblings, have lived for a long time, this is reassuring. If you have a family history of heart disease or strokes, your doctor may want to refer you to a lipid specialist.
Some people with Japanese ancestry have high HDL levels due to a lack of a protein called CETP. This is inherited in the genes.
Research has suggested that the changes in hormones that happen during the menopause can affect the way HDL works in the body, and HDL loses some of its protective effects in some women.
People who have an underactive thyroid may have high levels of HDL cholesterol.
Infections and inflammation
Recent research has suggested that HDL cholesterol changes in some situations, such as acute infection (infection which starts suddenly) and chronic (long term) conditions linked to inflammation, such as rheumatoid arthritis. More research is needed to fully understand why.
Other research suggests that high HDL cholesterol may be harmful if you are having dialysis for kidney disease, as it may make inflammation and tissue damage worse.
HEART UK recommendations for people with high levels of HDL
If you have a family history of early heart disease
Ideally your doctor should contact a lipid specialist for advice if:
- your HDL cholesterol level is higher than average with no obvious cause
- and other people in your family, such as a parent or sibling, have heart disease and were diagnosed below the age of 60.
If your total cholesterol and HDL cholesterol are high
If your total cholesterol is over 7.5mmol, with HDL over 2.5mmol, then your doctor should base their treatment decision mainly on your LDL cholesterol (and other non HDL-cholesterol).
Raised LDL cholesterol puts your heart health at risk so it needs to be brought under control.
Note that the TC/HDL ratio (which would otherwise be used) may be misleading if your HDL is high.
Look after your overall health
If you have high cholesterol, it’s important to lower your risk of heart disease overall. Try to adopt a healthy diet and lifestyle and manage any other health problems you have that can lead to heart disease. For example:
- get high blood pressure under control
- bring high blood sugar under control
- lose weight if you are overweight.
This is especially important for women leading up to, during and after the menopause.
Can medication help?
There are no medications that specifically target high HDL cholesterol, so the main thing is to lower your risk of heart disease overall.
We need more research to fully understand how HDL cholesterol works to develop ways to prevent and treat heart disease. This means studying how HDL lipoproteins work, and how this can be improved on, as simply raising the amount of HDL in the blood does not prevent disease.
If you have high HDL, this is not a reason to avoid lowering LDL cholesterol. Even though HDL is protective and LDL is harmful, high HDL cannot counteract high LDL.