What Is a Lipoprotein (a) Test?
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.
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 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
- uncontrolled diabetes
- renal failure
- nephrotic syndrome (a kidney disorder
characterized by protein loss, swelling, and elevated blood cholesterol and
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.
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. 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
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.
Preparation for the Test
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.
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?
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,
- 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 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