Acid Phosphatase, Prostatic

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Acid Phosphatase, Prostatic

Synonym/acronym: Prostatic acid phosphatase, o-phosphoric monoester phosphohydrolase, PAcP PAP.

Common use

To assist in staging prostate cancer and document evidence of sexual intercourse through semen identification in alleged cases of rape and sexual abuse.


Serum (1 mL) collected in a red-top tube.

A swab with vaginal secretions may be submitted in the appropriate transfer container. Other material such as clothing may be submitted for analysis. Consult the laboratory or emergency services department for the proper specimen collection instructions and containers.

Normal findings

(Method: Immunochemiluminometric)
Conventional & SI Units
Less than 3.5 ng/mL
Values are elevated at birth, decrease by 6 mo, increase at approximately 10 yr through puberty, level off through adulthood, and may increase in advancing age.


Acid phosphatases are enzymes found in many tissues, including the prostate gland, bone, spleen, liver, and kidney, as well as in red and white blood cells and platelets. Seminal fluid also contains high concentrations of acid phosphatase, and detection of this enzyme in vaginal swabs or from other physical evidence is used to investigate rape. Acid phosphatase activity is highest in the prostate gland; however, prostatic acid phosphatase (PAcP) levels are not significantly increased in the early stages of prostatic cancer, so this test is not recommended as a screening tool. Prostate-specific antigen has replaced PAcP for the staging of carcinoma of the prostate and diagnosis of metastatic adenocarcinoma of the prostate.

This procedure is contraindicated for



  • Assist in the investigation of sexual assault and rape
  • Assist with differential diagnosis of other disorders associated with elevated PAcP of nonprostatic origin
  • Evaluate the effectiveness of treatment for prostatic cancer (recurrence after prostatectomy). Levels decrease with effective treatment; rising levels are associated with a poor prognosis
  • Investigate or evaluate an enlarged prostate gland, especially if prostatic carcinoma is suspected

Potential diagnosis

Increased in

  • PAcP is released from any damaged cell in which it is stored, so diseases of the bone, prostate, and liver that cause cellular destruction demonstrate elevated PAcP levels. Conditions that result in abnormal elevations of cells that contain PAcP (e.g., leukemia, thrombocytosis) or conditions that result in rapid cellular destruction (sickle cell crisis) also reflect increased levels.

  • Acute myelogenous leukemia
  • After prostate surgery or biopsy
  • Benign prostatic hypertrophy
  • Liver disease
  • Lysosomal storage diseases (Gaucher’s disease and Niemann-Pick disease) (PAcP is stored in the lysosomes of blood cells, and increased levels are present in lysosomal storage diseases)
  • Metastatic bone cancer
  • Paget’s disease
  • Prostatic cancer
  • Prostatic infarct
  • Prostatitis
  • Sickle cell crisis
  • Thrombocytosis

Decreased in


Critical findings


Interfering factors

  • Drugs that may increase PAcP levels include alglucerase, androgens (females), and clofibrate.
  • Drugs that may decrease PAcP levels include alcohol, fluorides, heparin, oxalates, and phosphates.
  • Increased levels of PAcP may occur due to prostatic needle biopsy, cytoscopy, or recent digital rectal examination.
  • Increased levels of PAcP may occur with urinary retention.
  • PAcP is a very labile enzyme. Decreased levels may occur if specimens are not immediately processed in the laboratory.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in identification and documentation of sexual intercourse and can monitor treatment for prostate cancer.
  • Obtain a history of the patient’s complaints, especially alterations in urinary elimination. Obtain a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s genitourinary and reproductive systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and neutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues,  as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis. PAcP is very labile. Immediate separation from blood cells and freezing of the serum stabilizes PAcP.


  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Social and cultural considerations: Recognize anxiety related to test results, and offer support. Provide teaching and disease information, as appropriate. Counsel the male patient, as appropriate, that sexual dysfunction related to altered body function, drugs, or radiation may occur. Educate the patient regarding counseling services, as appropriate. Provide contact information, if desired, for the National Cancer Institute (
  • Social and cultural considerations: Recognize anxiety related to test results. Offer support, as appropriate, to patients who may be the victim of rape or sexual assault. Educate the patient regarding access to counseling services. Provide a nonjudgmental, nonthreatening atmosphere for discussing the risks of sexually transmitted diseases. Discuss problems the patient may experience (e.g., guilt, depression, anger) as a victim of rape or sexual assault.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include biopsy prostate, cystoscopy, cystourethrography voiding, PSA, retrograde ureteropyelography, semen analysis, and US prostate.
  • Refer to the Genitourinary and Reproductive systems tables at the back of the book for related tests by body system.
References in periodicals archive ?
29, CA 19-9, CA 125, Calcitonin, Cathepsin, CEA, Chromogranin, Colon-Specific Antigen, Cytokeratins, Estrogen Receptor, Ferritin, Gastrin, HCG, Insulin, Interferons, Interleukins, Lymphocyte Subtyping, Neuron-Specific Enolase, Nucleolar, Occult Blood, Oncogenes, Pancreatic Oncofetal Antigen, Pap Smear, Parathyroid Hormone, Progesterone Receptor, Prostatic Acid Phosphatase, Prostatic Specific Antigen, S-100 Protein, Serotonin, Sialic Acid, Squamous Cell Carcinoma Ag, TDT, Thymidine Kinase, Thyroglobulin, Tissue Polypeptide Antigen, and others.