Prostate Specific Antigen Blood Test (PSA)

Prostate spe­cif­ic anti­gen (PSA) is an enzyme pro­duced by the prostate which all men have in their blood­stream. The PSA blood test is a test which mea­sures the amount of prostate spe­cif­ic anti­gen in a man’s bloodstream. 

In gen­er­al, a healthy PSA lev­el range is between 0 – 4. Patients should seek fur­ther test­ing when the PSA lev­el is above this — or increas­es between tests. PSA test­ing is very indi­vid­u­al­ized and what is con­sid­ered abnor­mal for one man may be nor­mal for another. 

The rate of rise of the PSA over time is called PSA veloc­i­ty. A change in PSA of more than 0.5 ng/​ml per year may indi­cate a pres­ence of prostate cancer. 

For exam­ple, a man goes for his rou­tine screen­ing PSA test and it comes back at 2.0 ng/​mL. He is oth­er­wise healthy and his physi­cian is uncon­cerned by the result since 2.0 is in the nor­mal” range of 0 – 4 ng/​mL. But last year his PSA lev­el was 1.0 ng/​mL and the year before it was 0.5 ng/​mL. Due to the rate of rise (dou­bling each year), this indi­cates fur­ther eval­u­a­tion may be necessary. 

Most men (80%) with ele­vat­ed PSA have serum lev­els in the range of 4.0 to 10.0 ng/​ml. How­ev­er, numer­ous stud­ies have now shown that a high PSA veloc­i­ty may sig­nal a rapid­ly grow­ing can­cer regard­less of how high the absolute PSA lev­el is.

It is impor­tant to seek addi­tion­al med­ical advice if your PSA comes back abnor­mal. Your physi­cian may rec­om­mend a repeat test or biop­sy which involves tak­ing a small amount of tis­sue that is ana­lyzed under a micro­scope. The sam­ple is then giv­en a Glea­son Score which deter­mines the exis­tence or sever­i­ty of cancer.