LDL stands for low-density lipoprotein, a type of cholesterol found in your body. LDL is often referred to as bad cholesterol. This is because too much LDL causes a build-up of cholesterol in your arteries, which can lead to heart attacks and strokes.
High levels of good cholesterol—called high-density lipoprotein (HDL) in some individuals may decrease your risk of developing heart disease since HDL draws cholesterol away from your heart to be broken down in your liver.
Most doctors order an LDL test as part of routine exams to determine your risk for heart disease and decide if any treatment is necessary.
According to the National Heart, Lung, and Blood Institute, adults should have an LDL test at least once every five years. Typically, high cholesterol does not cause any visible symptoms, so you may not even know you have it without testing (NHLB).
If you have risk factors for developing heart disease, you may need to be tested more often. You are more likely to be at risk for heart disease if you:
- have a family history of heart disease
- smoke cigarettes
- are obese, meaning you have a body mass index (BMI) that is 30 or higher
- have low HDL (good cholesterol) levels
- have hypertension (or high blood pressure) or are receiving treatment for hypertension
- have diabetes
Your doctor may also order an LDL test if you are already being treated for high cholesterol. In this case, the test is used to determine if lifestyle changes, such as diet and exercise, or medications are lowering your cholesterol successfully.
Children normally do not need to be tested for LDL levels. However, children who are at a greater risk—such as those who are obese or who have diabetes or hypertension—should have their first testing done between the ages of 2 and 10.
High cholesterol does not generally cause any symptoms, so it is necessary to check for it routinely. High cholesterol raises your chances of having certain medical conditions, some of which are life-threatening. These include:
- coronary heart disease
- atherosclerosis, which is a build-up of plaque in your arteries
- angina, or chest pain
- heart attack
- carotid artery disease
- peripheral arterial disease
You should not eat or drink for 10 hours before the test, since food and drinks can temporarily change the levels of cholesterol in your blood. However, it is okay to have water. You may wish to schedule your test for first thing in the morning so that you do not need to fast during the day.
Make sure to tell your doctor if you are taking any over-the-counter drugs, prescription medications, or herbal supplements. Certain medications can affect your LDL levels, and your doctor may ask you to stop taking the medication or change the dose before your test.
An LDL test only requires a simple blood sample. This may also be called a venipuncture, or blood draw. The technician will begin by cleaning the area where the blood will be drawn with antiseptic. Blood is usually taken from a vein inside your wrist or on the back of your hand.
Next, the technician will tie an elastic band around your upper arm. This causes blood to pool in the vein. A sterile needle will then be inserted into your vein and blood will be drawn into a tube. You may feel mild to moderate pain that is similar to a pricking or burning sensation. You can usually reduce this pain by relaxing your arm while your blood is being drawn. The technician will remove the elastic band while the blood is being drawn.
When he or she is done drawing blood, a bandage will be applied to the wound. You should apply pressure to the wound for several minutes to help stop the bleeding and prevent bruising. Your blood will be sent to a medical lab to be tested for LDL levels.
Children under the age of 2 are too young to be tested for LDL. Also, individuals who have undergone an acute illness or stressful situation, such as surgery or a heart attack, should wait six weeks before having their LDL test done. Illness and acute stress can cause LDL levels to temporarily lower.
New mothers must wait six weeks after giving birth before having their LDL levels tested, since pregnancy temporarily increases their LDL cholesterol.
The chance of experiencing problems due to an LDL blood test is low. However, as with any medical procedure that breaks the skin, possible risks include:
- multiple puncture wounds due to trouble finding a vein
- excessive bleeding
- feeling light-headed or fainting
- hematoma, or a collection of blood under the skin