PSA is secreted by epithelial cells of the prostate gland and is present in small quantities in the serum of men with healthy prostate glands. Total serum PSA assay is an adjunct to a rectal examination for the screening of prostate cancer, as well as for follow-up of patients with diagnosed prostate cancer.
When total PSA is in the borderline range (4.0-10.0 ng/mL), the level of percent free PSA can help guide decisions about prostate biopsy. Clinicians can choose to have a borderline PSA automatically reflex to also include free PSA and percent free PSA.
Increased levels of total PSA are associated with an increased risk of prostate cancer, but may also be seen in subjects with benign prostatic hypertrophy.
Within the borderline range (4 to 10 ng/mL), the risk for prostate cancer varies substantially according to the patient’s age and the ratio of free PSA to total PSA (percent free PSA).
- The higher the percent free PSA the lower the risk of prostate cancer.
- Boston Heart will report the estimated probability of detecting cancer in a prostate biopsy. This applies to an individual who has had a digital rectal examination (DRE) that is not suspicious for prostate cancer.
- Total PSA will not reflex to free PSA when the level is greater than 10 ng/mL because the risk of prostate cancer is 50% or greater.
- These assays no longer show biotin interference in serum concentrations up to 1200 ng/mL.
- This test is performed using the Roche Diagnostics chemiluminescent method. Values obtained from different assay methods cannot be used interchangeably. PSA levels, regardless of value, should not be interpreted as absolute evidence of the presence or absence of disease.
1. Prestigiacomo AF, Stamey TA. Clinical usefulness of free and complexed PSA. Scand J Clin Lab Invest 1995;55 Suppl 221:32-34.
2. Thiel RP, Oesterling JE, Wojno KJ, et al. A multicenter comparison of the diagnostic performance of free prostate-specific antigen. Urology 1996;48(6A):45-50.