Acid Phosphatase

Updated: May 18, 2023
  • Author: Anas K Gremida, MD; Chief Editor: Daniela Hermelin, MD  more...
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Reference Range

In adults and elderly persons, the normal findings for acid phosphatase are 0.13-0.63 U/L (Roy, Brower, Hayden; 37°C) or 2.2-10.5 U/L (SI units). [1]

Normal findings in children are 8.6-12.6 U/mL (30°C), while normal findings in newborns are 10.4-16.4 U/mL (30°C). [1]



Conditions associated with elevations in prostatic acid phosphatase (PAP) include the following:

  • Benign prostatic hyperplasia

  • Prostatic infarction

  • Manipulation of the prostate through a massage or rectal examination


Collection and Panels

Specifics for collection and panels are as follows:

  • Specimen type: Blood serum

  • Container: Vacutainer, red/black top (preferred) or red top (see image below)

    empty para to satisfy content model empty para to satisfy content model
  • Collection method: Venipuncture

  • Specimen volume: 1 mL

  • Other instructions:

Related tests: Prostate-specific antigen (PSA)




Acid phosphatases are enzymes that are capable of hydrolyzing phosphate esters in an acidic environment.

Prostatic acid phosphatase (PAP), which is produced in the prostate, was the first major serum marker for prostate cancer. Metastasis of prostate cancer beyond the capsule, particularly to the bone, causes a rise in acid phosphatase level, with the level increasing in correspondence to the extent of the disease. [1] PAP was used widely for screening, staging, and posttreatment monitoring in prostate cancer, but its use has largely been displaced by that of PSA. [2, 3, 4]


Indications for testing of PAP include the following:

  • Additional prognostic information for predicting recurrence after radical prostatectomy for clinically localized prostate cancer

  • Additional monitoring of therapeutic response in prostate cancer treated by androgen ablation

  • Can also be used medicolegally as presumptive test to indicate the presence of semen in cases of sexual abuse

A study by Ponce and Zhang indicated that acid phosphatase can be used in determining the aggressiveness of prostate cancer. The investigators looked at assays they had developed for urinary glycoproteins and found that the expression of acid phosphatase is significantly higher in cases of aggressive prostate cancer than in individuals with nonaggressive prostate cancer. [5]