Also known as: LDL-C
Name: LDL cholesterol; LDL
Related tests: Total cholesterol, HDL cholesterol, Lipid profile, Triglycerides
Why is the test done?
To assess the risk of cardiovascular disease.
When is the test done?
The LDL cholesterol test is done as part of the lipid profile every four years for primary prevention if total cholesterol is above the reference range, and more often if other major cardiovascular risk factors are present or to monitor cholesterol-lowering treatment.
What samples are required?
A blood sample from a vein.
What is being analysed?
Low-density lipoproteins (LDL) carry cholesterol from the liver to the peripheral tissues through the bloodstream; when there is more cholesterol than the body needs, it can be released by LDL and deposited in the arteries, contributing to the formation of atherosclerotic plaque and so increasing the risk of cardiovascular disease. The LDL cholesterol test measures the amount of cholesterol contained in LDL; LDL cholesterol can also be calculated from total cholesterol, HDL cholesterol and triglycerides, provided triglycerides are not above 200-250 mg/dL.
How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?
How is it used?
The LDL cholesterol test is used to predict the risk of cardiovascular disease. Of the different forms of cholesterol that can be measured in plasma, LDL cholesterol is considered the most important in determining risk; any treatment is decided and monitored on the basis of LDL cholesterol.
When is it requested?
The LDL cholesterol test is generally requested as part of the lipid profile, together with total cholesterol, HDL cholesterol and triglycerides. LDL cholesterol may also be requested when particularly high total cholesterol values are found; in this case it is important to determine how much LDL and HDL cholesterol contribute to the total cholesterol value.
What does the test result mean?
LDL cholesterol is directly related to cardiovascular risk. According to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) guidelines, the aim of treatment, both dietary and drug-based, is to lower LDL cholesterol. The target values are:
• LDL < 100 mg/dL with heart disease or diabetes
• LDL < 130 mg/dL if at least two other major risk factors are present
• LDL < 160 mg/dL if one or no risk factor is present
Major risk factors include:
• smoking
• age (> 45 years for men and > 55 years for women)
• HDL cholesterol < 40 mg/dL
• high blood pressure (> 140/90 mmHg) or current treatment for high blood pressure
• a family history of coronary heart disease (at least one first-degree relative affected before the age of 55 for men and 65 for women)
[NOTE: high HDL cholesterol (> 60 mg/dL) is considered a protective factor, whose presence allows one risk factor to be removed from the total count.]
Is there anything else I should know?
The LDL cholesterol test requires fasting for about 12 hours before the blood sample, because LDL cholesterol is often calculated indirectly from other parameters, including triglycerides, which are affected by whether you have eaten. Some laboratories can measure plasma LDL directly, and in this case fasting is not needed.
1. What treatments are recommended for high cholesterol?
2. How much can cholesterol change in response to lifestyle changes, including exercise and diet?
3. From what age is LDL cholesterol testing recommended?
4. If there is a family history of high cholesterol, should I have LDL cholesterol tested at a young age?
1. What treatments are recommended for high cholesterol?
The first step in treating high cholesterol is changing your lifestyle: eating a diet low in saturated fat, reaching and maintaining a healthy weight and exercising regularly. If lifestyle changes are not enough, medicines can be used on a doctor’s prescription.
2. How much can cholesterol change in response to lifestyle changes, including exercise and diet?
A diet low in saturated fat (with less than 7% of calories from saturated fat) is generally enough to lower LDL cholesterol by about 10% and is a first-line measure. If diet is not enough, additional medicines can be used.
3. From what age is LDL cholesterol testing recommended?
Everyone over 30 should be screened for high cholesterol, ideally as part of a lipid profile, at least once every five years.
4. If there is a family history of high cholesterol, should I have LDL cholesterol tested at a young age?
Children of people with a family history of high cholesterol and heart disease are sometimes screened for total and LDL cholesterol at a young age. However, drug treatment for high cholesterol in people under 18 must be prescribed with caution, based on clinical judgement of the severity of the case.