Prostatic acid phosphatase (PAP)

The PAP test is a blood test that measures prostatic acid phosphatase (an enzyme found in men, primarily in the prostate gland and semen) to determine the health of the prostate gland. Prostate dysfunction results in the release of PAP into the blood.

Prostatic acid phosphatase test; Serum acid phosphatase; Male PAP test

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band or blood pressure cuff is placed around the upper arm. This causes veins below the band to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

This test usually does not require special preparation. As with any blood test, the health care provider may limit certain foods or medications shortly before the test to assure an accurate sample.

Drugs that can interfere with PAP measurements include fluorides, oxalates, clofibrate, and alcohol

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing in the area.

This test is most often performed to determine whether you have prostate cancer, an abnormality of the prostate gland, or to follow the response of prostate cancer to treatment.

This test is no longer used routinely. The availability of the more sensitive and specific PSA assay has largely replaced the PAP test's clinical use.