Total PSA (Prostate Specific Antigen) is used in the Tumour Marker Lab primarily in the management of prostate cancer. It is used as a diagnostic test, along with Free PSA and the Free vs.Total PSA Ratio. It is of significant value in detecting metastatic or persistent disease following treatment. Persistent elevation following treatment or increase in post treatment levels are indicative of recurrent or residual disease.
PSA is of unknown value as a population screening test. Although there is good evidence that it increases the detection rate of early stage, clinically significant, prostate cancers, there is little evidence to date that such early detection leads to reduced mortality, the "gold standard" for evaluating screening tests. Fit men (men with at least 10 years life expectancy) between the ages of 50 and 70 should be made aware of the availability of PSA as a detection test for prostate cancer. They should be aware of the potential benefits and risks of early detection so they can make an informed decision as to whether to have the test performed.
The PSA assay is a MEIA Abbott AxSYM method. Samples are serum (preferred) or plasma.
Age related Reference Ranges:
<50 years = <2.5 µg/L
50-60 years = <3.5 µg/L
60-70 years = <4.5 µg/L
>70 years = <6.5 µg/L
Lower Limit of Detection (LLD) = 0.02 µg/L
Borderline (age dependent) = <10.0 µg/L
Interferences: HAMA, prostate manipulation including rectal examination, diagnostic intervention, biopsy, prostatectomy or prostate massage. It is recommended that PSA serum samples be taken prior to or 2-3 weeks after any of the above procedures.