LDL cholesterol

All of the cells in our body need cholesterol – for example, to do things like make vitamin D or certain hormones. 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) mainly include two types of cholesterol known as HDL cholesterol and LDL cholesterol. HDL stands for "high-density lipoprotein" and LDL stands for "low-density lipoprotein."

LDL cholesterol makes up the majority of the cholesterol in your blood: more than two thirds. Cholesterol is transported in this form from the liver (where most of it is made) to the rest of the body. LDL cholesterol is often referred to as "bad cholesterol" because high levels are associated with a higher risk of cardiovascular disease.

The amount of LDL cholesterol is usually determined together with HDL 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 LDL cholesterol levels can be used to assess your risk of cardiovascular disease.

LDL 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 cholesterol levels can give you an idea, though:

If you have low LDL cholesterol levels, you won't usually need any further tests. LDL cholesterol is only rarely very low.

Very low LDL cholesterol can be caused by various medical conditions. For example:

• Overactive thyroid (hyperthyroidism)
• Liver diseases
• Chronic infections
• Cancer

If you take cholesterol-lowering drugs such as statins, a very high dose can lead to very low levels too.

Low LDL cholesterol levels are usually harmless or even achieved on purpose as part of a treatment goal. But it still makes sense to have them checked out by a doctor. They could be a sign of a serious illness or that you need to lower the dose of your medication.

The medical term for too much LDL cholesterol in your blood is "hypercholesterolemia." Generally speaking, the higher your LDL cholesterol, the higher your risk of conditions affecting your blood vessels, such as peripheral artery disease (PAD), heart attack or stroke. Although LDL cholesterol is a major risk factor here, the risk can't be assessed based on LDL cholesterol levels alone. Other levels are important too – like the amount of HDL and total cholesterol.

Note: High LDL 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.

High LDL cholesterol levels can be caused by various things. Certain lifestyle habits (like not getting enough exercise or eating an unbalanced diet) can increase the levels. They are also often high in people who are very overweight.

Sometimes LDL cholesterol levels increase due to a condition such as diabetes or an underactive thyroid gland. Chronic liver and kidney diseases can also have this effect. So can certain medications, like hormonal contraceptives, beta blockers and steroids.

Genes play a role in some cases: About 0.2 to 0.5% of all people have a condition known as familial hypercholesterolemia. They already have high LDL cholesterol in childhood due to an inherited genetic defect.

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

People with high LDL cholesterol might have a greater risk of cardiovascular disease. It is then often a good idea to lower these 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 lower your LDL cholesterol. Recommendations include

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

If that's not enough to make a difference or if you have a high risk of cardiovascular disease, cholesterol-lowering drugs such as statins may be considered. This medication is also recommended if your high cholesterol is caused by your genes.