PSA stands for Prostate Specific Antigen. The word ‘Specific’ means that this enzyme is produced only by prostate cells – whether normal prostate cells or prostate cancer cells. No other cells in the body – lung, intestine, liver, etc. – make PSA. The purpose of PSA is to keep semen (the white substance ejaculated during sexual intercourse) liquefied. PSA is also leaked into the bloodstream by normal prostate cells and can be measured by a simple blood test as was done with your PSA. PSA tests vary based on each person and testing numbers can be unique to an individual. This means that while a 4.4 PSA could be high for one person, it may be normal, or even low for somebody else.