PSA is a glycoprotein monomer secreted by the prostate epithelium and produced by prostate cancer cells. The measurement of PSA has been determined to be of significant value in detection of metastatic or persistent disease and in evaluation of patients following surgical or medical treatment of prostate cancer. Continued elevation of PSA levels is indicative of recurrent or residual disease.
When used as a screening procedure in the general population, unless highly elevated, random results are not meaningful. It is of value to study the rate of change/increase over specified periods of time. Early studies appear to indicate that in patients with cancer, PSA changes exponentially. In patients with Benign Prostatic Hyperplasia, PSA increases linearly and at a slower rate.
Although studies indicate that digital rectal examination prior to obtaining of the blood sample for PSA testing does not significantly affect the result, in some cases it may cause elevation. Therefore, it is recommended to obtain the specimen for PSA prior to digital rectal examination.
PSA testing is performed Monday through Saturday with results available the following working day.