What Is a Lipoprotein-a Test?
Low-density lipoprotein (LDL) or “bad cholesterol” is typically associated with an increased risk for heart attack and stroke. Lipoproteins are substances made up of protein and fat. LDLs can be separated by type and 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. (Mayo Clinic)
The Lp (a) test can be used by your doctor to measure the levels of Lp (a) in your bloodstream. Information from this test can be used to determine your risk for 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.
What Is the Purpose of the Test?
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 lifespan, 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)
Because levels of Lp (a) are genetically determined, there is no specific way to decrease Lp (a) levels. (Cleveland Clinic) However, your doctor will likely treat your overall cholesterol levels, both LDL and HDL (high-density lipoproteins), as well as triglycerides (another type of fat found in the blood that is important in its affect on cardiovascular health). This can be done through aggressively modifying your diet, starting a consistent exercise program, and taking medications to lower the cholesterol and lipoproteins. .
When Is the Test Ordered?
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. Additionally, your doctor may order this test if you have a family history of premature heart disease (heart disease before the age of 55) or if you have an existing heart condition or other vascular disease.
The Lp (a) test may be ordered if you have 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.
Preparation for the Test
In order to prepare for the Lp (a) test, you will be asked to fast for 12 hours before the test. This means you will not be able to take any food or liquid, except water, by mouth before the test. If you smoke, you will also be asked to refrain from smoking 12 hours before the test. Patients 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.
How Is the Test Administered?
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.
What Are the Risks of the Test?
Patients undergoing the Lp (a) test may experience some discomfort when the blood sample is drawn. Needle sticks may result in pain at the injection site during the test. Following the test, patients may experience pain or throbbing at the injection site. Bruising may also occur after the test is completed.
The risks of the Lp (a) test are minimal. These risks are common to most blood tests. Potential risks for the test 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
Understanding Your Results
The results of the Lp (a) test will vary, depending on the laboratory where the sample was analyzed. Normal values for this test are below 30 mg/dL (milligrams per deciliter). In many instances, patients will have no detectable levels of Lp (a) in their bloodstream. If your results are above the 30 mg/dL threshold, this may place you at increased risk for atherosclerosis, heart attack, or stroke.