LDL Cholesterol Test

1) To identify people at high risk of developing cardiovascular disease

People who eventually go on to develop cardiovascular disease often have had a high LDL-C for many years before they develop any symptoms from it. Therefore, measuring LDL-C can be useful to help predict your chances of developing cardiovascular disease, allowing you to do something about it before it causes you any problems.

In fact, in the UK, the first line lipid test used in risk calculators to identify people with ‘high cardiovascular risk’ is not LDL-C, but another parameter derived from the lipid profile called the total cholesterol : HDL cholesterol ratio. The LDL-C would almost always be checked at the same time, and does provide additional information to the total cholesterol : HDL cholesterol ratio. For example, if it is very high, this can sometimes indicate specific conditions such as ‘familial hypercholesterolaemia’.

2) In people known to be at high risk of developing cardiovascular disease, to monitor their response to treatment

If you have been found to be at increased risk of heart disease, you will usually be advised to make some lifestyle improvements, such as improving your diet, and you may also be offered treatments which can lower your LDL-C, such as statins. In either case, the LDL-C would then usually be monitored to find out if the treatments or changes you have made to your diet are working.

3) In people with a family history of premature cardiovascular disease and a suspected genetic cholesterol condition

Familial hypercholesterolemia affects approximately 1 in 250 people and although not the commonest cause of high cholesterol early detection can save lives. Genetic testing is the test of choice but, depending on who is available for testing, LDL-C can be used to indicate the most likely affected relative in whom to do the initial genetic test.

LDL-C, as part of a lipid profile, is commonly tested by your GP when you reach the age of 40, as part of a routine cardiovascular health check.

It may be checked at other times if you are thought to be at increased risk of cardiovascular disease for another reason.

Finally, it will likely be checked at regular intervals if you have been prescribed treatments to help lower your LDL-C, such as statins.

Elevated concentrations of LDL-C increase your risk of developing cardiovascular disease. This is used in conjunction with other factors such as age, gender, smoking, blood pressure, being overweight, to estimate your chances of developing heart disease in the future. If this indicates you might be at high risk, the LDL-C is then used as a ‘target’ for you to aim for. Your doctor would then usually recommend dietary changes and possibly medical treatments to help reduce your LDL-C down to this target.

In the UK, the target LDL-C for people at high risk of cardiovascular disease is usually ‘no more than 2.0 mmol/L’. A fall of 40% from the pre-treatment level is also used as an alternative target. Bear in mind that the lower your LDL-C, the lower your chances of cardiovascular disease, so there are additional benefits down to an LDL-C of zero (0 mmol/L). Furthermore, it means that if your LDL-C was very high to start off with (when getting down to 2.0 mmol/L may not be possible), any reduction you get with dietary improvements or medications will be beneficial.

If you are not considered to be at high risk of cardiovascular disease, there is no official target for LDL-C. However, many doctors would consider no more than 3.0 mmol/L as desirable.

There is condition which runs in families called “familial hypercholesterolaemia” in which LDL-C is very high – usually over 4.9 mmol/L in adults. Some people, though not all, who have an LDL-C this high, have familial hypercholesterolaemia. This is an inherited condition which is important to pick up, as if it isn’t treated there is a high risk of heart disease at a young age. Furthermore, as it is inherited, other family members might be affected. Anyone suspected of having familial hypercholesterolaemia should be referred to a specialist lipid clinic.

LDL-C should be measured when a person is healthy. LDL-C is temporarily low during acute illness, immediately following a heart attack, or during stress (like from surgery or an accident). You should wait at least six weeks after any illness to have LDL-C measured.

In women, cholesterol is high during pregnancy. Women should wait at least six weeks after the baby is born to have LDL-C measured.

The first step in treating high LDL-C is adoption of a heart healthy diet and a healthy weight and adoption of regular aerobic exercise. For advice on how to lower cholesterol through diet and lifestyle, visit the HEART UK website.

If dietary changes alone do not adequately lower LDL-C, drugs may be prescribed. A class of drug called ‘statins’ is usually used first line. Statins have been around for many years and there is excellent evidence that they are effective in lowering LDL-C, and have a low rate of side effects. For information on drugs that lower cholesterol, visit the HEART UK website.