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Prostate Specific Antigen (PSA)
Principle
Prostate cancer is the most common malignancy in men in the United States and the second leading cause of cancer-related deaths. Early detection improves treatment outcomes.
Prostate Specific Antigen (PSA) is a glycoprotein with a molecular weight of approximately 34,000 Daltons. PSA is present in normal, benign hyperplastic, and malignant prostatic tissue, as well as in prostatic fluid and seminal plasma. In serum, PSA circulates in several molecular forms; however, only free PSA and PSA complexed with alpha-1-antichymotrypsin (ACT) are immunologically active. The VITROS PSA assay measures total PSA, which includes both free and ACT-complexed PSA.
Elevated serum PSA concentrations may be observed in prostate cancer, benign prostatic hyperplasia (BPH), or inflammatory conditions affecting adjacent genitourinary tissues. PSA levels are typically low or undetectable in healthy men and in men with non-prostatic malignancies. PSA testing alone is not recommended as a screening tool due to overlap between benign and malignant conditions.
Serial PSA measurements are valuable in monitoring prostate cancer progression, detecting residual or recurrent disease following radical prostatectomy, and assessing response to therapy including surgery, radiation, and anti-androgen treatment. PSA levels also assist in evaluating disease stage and therapeutic effectiveness.
Specimen Requirements
Specimen
Collection
Processing
Storage and Transport
Store/transport at 15–30°C for ≤8 hours; 2–8°C for ≤48 hours; freeze at ≤ –20°C if delayed. Avoid repeated freeze–thaw cycles.
Unacceptable Specimens
Hemolyzed or unseparated specimens.
Method
Enhanced Chemiluminescence.
Normal Range
0–4 ng/ml
Turnaround Time
References
- Wang MC, Papsidero LD, Kuriyama M, et al. Prostate antigen: a new potential marker for prostatic cancer. The Prostate. 2:89-96; 1981.
- Papsidero LD, Wang MC, Valenzuela LA, et al. A prostate antigen in sera of prostatic cancer patients. Cancer Research. 40:2428-2432; 1980.
- Oesterling JE. Prostate specific antigen: a critical assessment of the most useful tumor marker for adenocarcinoma of the prostate. Journal of Urology. 145:907-923; 1991.