Tartrate-Resistant Acid Phosphatase
Does this test have other names?
Bone turnover marker, tartrate-resistant acid phosphatase 5b, TRAP
What is this test?
This test looks for the chemical tartrate-resistant acid phosphatase (TRAP) in your
blood. This test can also be done on bone marrow.
TRAP can appear in your blood if you have hairy cell leukemia, a kind of cancer that
attacks your blood and bone marrow. It can also appear when bone is broken down in
your body, as in the disease osteoporosis or in cancers that have spread to the bone.
Types of cancers that are likely to spread to the bones are cancers of the breast,
prostate, kidneys, lung, pancreas, colon/rectum, stomach, thyroid, and ovaries.
If you have hairy cell leukemia, too many stem cells in your bone marrow develop into
abnormal lymphocytes, a type of white blood cell. The abnormal cells build up in your
marrow, leaving less room for health white blood cells. The abnormal lymphocytes make
TRAP, which appears in your bloodstream.
Why do I need this test?
You may need this test if your healthcare provider suspects that you have hairy cell
leukemia. Symptoms of hairy cell leukemia include:
Fatigue or weakness
Fever, chills, or frequent infections
Skin that bruises easily
Shortness of breath during normal physical activity
Unexplained weight loss
Pain below your ribs
Painless lumps in the neck, underarm, stomach and groin
You may also need this test if you have another type of cancer and your healthcare
provider wants to find out if it has spread to your bones.
What other tests might I have along with this test?
Your healthcare provider may also order other blood tests, scans, and a biopsy of
your bone marrow.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Normal results are negative, meaning that TRAP wasn't found in your blood. You don't
have hairy cell leukemia. A positive result means that your bones are breaking down
for some reason. If your healthcare provider has ordered other tests that show you
have hairy cell leukemia, it will help confirm the diagnosis.
If you have a positive result but not hairy cell leukemia, your provider may order
other tests to confirm another cancer or another cause, such as osteoporosis.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
No other factors affect your test results.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.