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 they include lipoprotein(a), or Lp(a). 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 (hardening of the arteries). Although LDL in general is affected by both your lifestyle (exercise and diet) and family history, Lp(a) is typically determined by genetics and not lifestyle.
The Lp(a) test can be used by your doctor to measure the levels of Lp(a) in your bloodstream. Results of this test help to determine your risk of developing heart disease. Typically, your doctor will routinely test for total cholesterol levels, LDL, HDL (high-density lipoprotein), and triglycerides. If you have a family history of heart disease, heart attacks, heart problems, or your high cholesterol or LDL levels do not respond to treatment, he or she may perform an Lp(a) test to get more information about your health.
The Lp(a) test is typically ordered by a doctor if you have other risk factors for developing heart disease. Although Lp(a) levels are genetically determined and remain constant throughout your life, there are specific conditions that 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 (an underactive thyroid gland)
- uncontrolled diabetes
- renal failure
- nephrotic syndrome (a kidney disorder characterized by protein loss, swelling, and elevated blood cholesterol and lipoproteins)
Lp(a) levels are genetically determined and remain relatively stable. However, your doctor will likely treat your overall cholesterol levels, both LDL and HDL, as well as triglycerides (another type of fat found in the blood that’s important in its effect on cardiovascular health). This can be done through aggressively modifying your diet, starting a consistent exercise program, and taking medications to lower cholesterol and lipoproteins.
The Lp(a) test is not commonly used when evaluating cholesterol levels. Your doctor may order this test if the results of other blood tests reveal an increased risk for heart disease. Your doctor may also order this test if you have a family history of premature heart disease (heart disease before the age of 55 years) or if you have an existing heart condition or other vascular disease.
The Lp(a) test may be ordered if you’ve recently had a heart attack or stroke. The test may also be ordered for postmenopausal women who have increased risk factors for the development of heart disease, including hypertension, diabetes, or other vascular diseases.
In order to prepare for the Lp(a) test, you’ll be asked to fast for 12 hours beforehand. This means you won’t be able to take any food or liquid, except water, by mouth 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 accompanied by 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 will be sent to a lab for analysis. The lab reports will be sent to your doctor who will be able to provide you with more information about the results and what they mean.
People undergoing the Lp(a) test may experience some discomfort when the blood sample is drawn, as is the case with any blood test. Needle sticks may result in pain at the injection site during the test. Following the test, you may experience pain or throbbing at the injection site. Bruising may also occur after it is completed.
The risks of the Lp(a) test are minimal. Potential, but rare, risks include:
- difficulty obtaining 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
- development of infection where the skin is 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 mg/dL (milligrams per deciliter). 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 place you at increased risk for atherosclerosis, heart attack, or stroke. Talk with your doctor about your results.