Acid Phosphatase ( Prostatic Acid Phosphatase PAP)

Test Description

Acid phosphatase, also known as prostatic acid phosphatase (PAP), is an enzyme

found primarily in the prostate gland, with high concentrations found in the seminal

fluid. It is found in smaller concentrations in the kidneys, liver, spleen, bone

marrow, erythrocytes, and platelets. Acid phosphatase is used to diagnose advanced

metastatic cancer of the prostate and to monitor the patient’s response to therapy

for prostate cancer.

In the past, this test has been considered a tumor marker for prostatic cancer.

However, with the advent of the prostate-specific antigen (PSA) test, monitoring of

the acid phosphatase is decreasing in popularity. An additional use of acid phosphatase

testing is testing for its presence in vaginal secretions during the investigation

of cases of alleged rape.

THE EVIDENCE FOR PRACTICE

According to guidelines of the American Academy of Pediatrics for evaluation of sexual

abuse in children (http://pediatrics.aappublications.org/cgi/content/full/116/2/506), a high

acid phosphatase level in a child is suggested as one criterion for reporting suspected sexual

abuse.

Normal Values

2.2–10.5 U/L (37–175 nkat/L SI units)

Possible Meanings of Abnormal Values

Increased                                                                                                                                       

Acute renal impairment

Bone metastases

Breast cancer

Cirrhosis

Eclampsia

Gaucher’s disease

Hemolytic anemia

Hepatitis

Hyperparathyroidism

Liver tumor

Multiple myeloma

Obstructive jaundice

Paget’s disease

Prostate cancer

Sexual abuse

Contributing Factors to Abnormal Values

               • Hemolysis of the blood sample may alter test results.

               • Any manipulation of the prostate gland, including rectal examination or cystoscopy,

                should be avoided for 2 days before the test.

               • Acid phosphatase levels vary during the day. Multiple tests of acid phosphatase

               should be drawn at the same time each day.

               • Drugs that may increase acid phosphatase: anabolic steroids, androgens, clofibrate.

               • Drugs that may decrease acid phosphatase: alcohol, fluorides, oxalates, phosphates.

  

Interventions/Implications

Pretest

• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.

• No fasting is required before the test.

Procedure

• A 7-mL blood sample is drawn in a collection tube containing a silicone gel. The tube

should be kept on ice.

• Gloves are worn throughout the procedure.

Posttest

• Apply pressure at the venipuncture site. Apply dressing, periodically assessing for continued

bleeding.

• Label the specimen and transport it to the laboratory immediately.

• Report abnormal findings to the primary care provider.