Prostatic Acid Phosphatase (PAP; PSAP): Optimal Testing Recommendations
- Use prostate-specific antigen (PSA) because PAP results do not provide any additional clinical information compared to PSA results.
Guidelines for Test Utilization
What does the test tell me?
This test is not useful. [back to top]
When should I order this test?
Do not order this test. [back to top]
When should I NOT order this test?
Do not use this test to screen prostatic malignancy. [back to top]
How should I interpret the result?
Interpretation of PAP if ordered should only be within the context of the PSA results. Normalization in serum PAP concentrations occurs following successful therapy, while recurrent or residual disease has been associated with elevated concentrations of PAP. [back to top]
Is the test result diagnostic/confirmatory of the condition?
The PAP test is not diagnostic or confirmatory. [back to top]
Are there factors that can affect the lab result?
Elevated PAP concentrations can occur due to benign prostatic hyperplasia, prostatic infarction, prostatitis and manipulation of the prostate gland. PAP is expressed in many cancers (melanoma, lymphoma, cancer of the testis, and urothelial cancer) and shows that PAP is not prostate-specific. [back to top]
Are there considerations for special populations?
Not applicable. [back to top]
What other test(s) might be indicated?
Serum PSA is indicated as PAP is an adjuvant biomarker and should never be used alone. [back to top]
Burnett AL, Chan DW, Brendler CB, Walsh PC. The value of serum enzymatic acid phosphatase in the staging of localized prostate cancer. J Urol. 1992;148:1832-4.
Moul JW, Connelly RR, Perahia B, McLeod DG: The contemporary value of pretreatment prostatic acid phosphatase to predict pathological stage and recurrence in radical prostatectomy cases. J Urol 1998;159:935-940
Beaver TR, Schultz AL, Fink LM, et al: Discordance between concentration of prostate-specific antigen and acid phosphatase in serum of patients with adenocarcinoma of the prostate. Clin Chem 1988;34:1524
Last reviewed: March 2021. The content for Optimal Testing: AACC's Guide to Lab Test Utilization has been developed and approved by the AACC Academy and AACC's Science and Practice Core Committee.
As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients received the highest quality and most useful laboratory tests. AACC's Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.