Low-density lipoprotein (LDL), or “bad cholesterol,” is typically associated with an increased risk of heart attack and stroke. Lipoproteins are substances made up of protein and fat. LDLs can be separated by type and if they include lipoprotein(a), or Lp(a).
Typically, doctors test for:
- total cholesterol levels
- HDL (high-density lipoprotein)
- triglycerides, another type of fat found in the blood
However, they may perform an Lp(a) test to get more information about your health. A doctor can use an Lp(a) test to measure the levels of Lp(a) in your bloodstream, which are related to your risk of heart disease.
They may order the test if you have a family history of heart disease, heart attacks, or heart problems. They may also give you the test if your high cholesterol or LDL levels do not respond to treatment.
The Lp(a) test is typically ordered by a doctor if you have other risk factors for heart disease. Results of this test help determine your risk.
Increased amounts of Lp(a) in the body are associated with inflammation in the walls of the arteries. This can lead to changes in the blood vessels, including atherosclerosis. This is a hardening of the arteries.
Although LDL in general is affected by exercise, diet, and family history, Lp(a) is typically determined by genetics. Levels of Lp(a) remain pretty constant throughout your life, but specific conditions can increase the amount of Lp(a) in your body. These include:
- estrogen depletion
- hypercholesterolemia, a condition characterized by high levels of blood cholesterol
- severe hypothyroidism, or an underactive thyroid gland
- uncontrolled diabetes
- renal failure
- nephrotic syndrome, which is a kidney disorder characterized by protein loss, swelling, and elevated levels of blood cholesterol and lipoproteins
The Lp(a) test is not commonly used when evaluating cholesterol levels. However, your doctor may order this test if the results of other blood tests reveal an increased risk of heart disease. Your doctor may also order this test if you:
- have a family history of heart disease before the age of 55 years
- have an existing heart condition or other vascular disease
- have recently had a heart attack or stroke
- are postmenopausal and have increased risk factors for heart disease, including hypertension, diabetes, or other vascular diseases
To prepare for the Lp(a) test, you’ll need to fast for 12 hours beforehand. This means you won’t be able to eat or drink anything except water before the test. If you smoke, you’ll also be asked to refrain from smoking 12 hours before the test.
People who have had a recent infection with a fever may need to wait several days before having the test. Talk to your doctor about your recent health history to determine the best time to have the testing done.
The Lp(a) test is performed on blood taken from a standard blood draw. Typically, a nurse or doctor will draw a small blood sample from your arm in a clinical setting. The blood will be collected in a tube and sent to a lab for analysis. The lab reports will be sent to your doctor, who can give you more information about the results and what they mean.
You may experience some discomfort when the blood sample is drawn, as with any blood test. Needle sticks may be painful during the test. Following the test, you may experience pain or throbbing at the injection site. Bruising may also occur.
The risks of the Lp(a) test are minimal. Rare but possible risks can include:
- difficulty getting a sample, resulting in multiple needle sticks
- excessive bleeding at the needle site
- fainting as a result of blood loss
- the accumulation of blood under the skin, known as a hematoma
- infection where the skin was broken by the needle
The results of the Lp(a) test will vary depending on the laboratory where the sample was analyzed. Normal values for this test are less than 30 milligrams per deciliter (mg/dL). In many instances, people will have no detectable levels of Lp(a) in their bloodstream. If your results are greater than the 30 mg/dL threshold, this may indicate increased risk of atherosclerosis, heart attack, or stroke.
Talk with your doctor about your results. They will likely treat your overall cholesterol levels, both LDL and HDL, as well as triglyceride levels. This may involve aggressively modifying your diet, starting a consistent exercise program, and taking medications to lower cholesterol and lipoproteins.