HDL cholesterol

All of the cells in our body need cholesterol – to do things like make vitamin D or certain hormones, for example. But cholesterol is not water-soluble, so it can only be transported in the blood in the form of tiny particles called lipoproteins. Lipoproteins are made up of protein and cholesterol “parcels.” Your overall cholesterol levels (total cholesterol) are mainly made up of two types of cholesterol known as HDL cholesterol and LDL cholesterol. HDL stands for “high-density lipoprotein,” and LDL stands for “low-density lipoprotein.”

About one quarter of all cholesterol in your blood is HDL cholesterol (HDL-C). Excess cholesterol is transported in this form to the liver, where it can be broken down. HDL-C is often referred to as “good cholesterol” because high HDL-C levels tend to be associated with a lower risk of cardiovascular disease.

The amount of HDL cholesterol is usually determined together with LDL and total cholesterol, as well as other blood lipid levels. Abnormal levels may be a sign that your body can't metabolize (process) lipids properly. Together with the other levels, your HDL-C levels are used to estimate your risk of cardiovascular disease.

HDL cholesterol is also measured with your total cholesterol as part of the general health check-up offered in Germany (“Gesundheits-Check-up” or "Check-up 35"). People with public health insurance can have this general health check-up every three years from the age of 35. Younger people (between the ages of 18 and 35) can have this check-up once.

To measure your cholesterol, the doctor takes a sample of blood – usually from a vein in your arm.

Meals hardly influence cholesterol levels, so you don't necessarily have to do the blood test on an empty stomach. But doctors usually recommend fasting beforehand anyway because other blood levels are often measured at the same time, and those may be affected by meals. If you're asked to come on an empty stomach, you shouldn't eat or drink anything other than still water in the 8 hours before the appointment.

The reference range values may differ from lab to lab because they sometimes use different test procedures. The following levels can give you an idea, though:

Low HDL cholesterol levels may be associated with a higher risk of diseases such as peripheral arterial disease, heart attacks or strokes. But HDL cholesterol levels don't mean that much when considered alone. Other blood lipid levels – like the amount of LDL cholesterol or triglycerides – are important too.

Note: HDL cholesterol is just one of several risk factors. Your personal risk of cardiovascular disease can only be assessed if all the factors are considered together. Other important factors include smoking, your age, your biological sex and whether you already have other medical conditions such as diabetes, high blood pressure or kidney problems.

Low HDL cholesterol levels can be caused by various things. They are often due to certain habits such as not getting enough exercise or eating an unbalanced diet. People who are very overweight may have low levels too.

Sometimes HDL cholesterol levels also decrease due to illnesses such as diabetes or chronic liver and kidney disease. Certain medications (like hormonal contraceptives, beta blockers and steroids) can have this effect as well.

People who have problems with the metabolism (processing) of carbohydrates or increased triglyceride levels may also have low HDL cholesterol.

If you have low HDL cholesterol, it's important to find out why. If it's caused by an illness, that illness should be treated.

People with low HDL cholesterol might have a greater risk of cardiovascular disease. It can then be a good idea to increase the HDL cholesterol levels – by how much mainly depends on their personal risk. The doctor can assess this risk based on certain risk factors and other blood levels.

You can do a lot yourself to increase your HDL cholesterol. Recommendations include

• getting more exercise,
• losing weight (if you're overweight),
• eating a balanced diet, and
• not smoking.

Doing these things generally reduces your risk of cardiovascular disease too.

High HDL cholesterol levels can increase the risk of cardiovascular disease – especially if you already have other risk factors.

Very high HDL cholesterol levels can be caused by your genes, for example. As a result, too much HDL cholesterol is produced, or it cannot be broken down properly. Other factors that can increase HDL cholesterol include hard physical work, competitive sports and alcohol consumption.

As is advised for low levels, it makes sense to find out what the causes are together with your doctor. They can then determine whether something needs to be done to reduce the levels and, if so, what could help.