Acid Phosphatase Test

Alternate Names
prostatic acid phosphatase test
serum acid phosphatase test
PAP test
tartrate-resistant acid phosphatase test
TRAP test

Definition of Acid Phosphatase Test

This test measures the level of acid phosphatase in the blood. Acid phosphatase is an enzyme produced in the prostate gland, semen, liver, spleen, blood cells, and bone marrow. If these organs and tissues are not functioning right, they may release acid phosphatase into the bloodstream.

Who is a candidate for the test?

The acid phosphatase test is used primarily to diagnose and stage cancer of the prostate and to monitor the effect of the treatment. It may also be used to detect damage to the heart, liver, and other organs.

How is the test performed?

To measure the amount of acid phosphatase in the blood, a blood sample is taken, usually from a vein in the arm. First, the skin over the vein is cleaned with an antiseptic. A tourniquet is wrapped around the upper arm to enlarge the veins. A small needle is inserted into a vein, and blood is collected for testing in the laboratory. After the tourniquet is removed, a cotton ball is held over the needle site until bleeding stops.

What is involved in preparation for the test?

A person should request specific instructions from his or her doctor.

What do the test results mean?

A healthy level of acid phosphatase in the blood is 0 to 0.8 U/L (units per liter). Abnormal levels of acid phosphatase in the blood may indicate one or more of the following:

• prostate cancer that has spread outside the prostate gland, often to bone
• decreased flow of blood to the prostate gland
• Paget disease, a disease in which bones thicken and soften
• anemia, which is a low number of red blood cells
• infection
• prostatitis, which is an inflammation of the prostate gland
• thrombophlebitis, which is inflammation and small blood clots in a vein, usually in the leg
• Gaucher disease, which is a lipid metabolism disorder
• hyperparathyroidism, which is a condition caused by increased activity of the parathyroid gland
• heart attack
• kidney disease, such as end-stage renal disease
• physical stimulation of the prostate gland, which can be done by prostate examination, colonoscopy, or enemas
• multiple myeloma, which is a malignancy beginning in the plasma cells of the bone marrow