This is and interesting explanation of PSA the DRE by a doctor. I thought this could be of value and clearly edifying. The only comment not mentioned is that the PSA levels mentioned do not reference the significance of ethnicity relative to raised PSA levels. Nonetheless this is good primer.
The PSA, or prostate specific antigen, is a protein made by the cells in the prostate gland. The prostate gland is located right next to the bladder, and provides some of the liquid that is part of semen. The urinary tract passes right through the middle of the prostate gland, like the hole in a doughnut, so if the prostate gland gets enlarged, the urine flow can be reduced or cut off.
A certain amount of PSA circulates in the blood, and this is measured as a rough estimate of the size of the prostate gland. The larger the gland, the higher the PSA level. Prostate cancer usually causes a high PSA level, but not always. In general, the worse the cancer, the higher the PSA level. The most common reason for a high PSA level is the benign growth of the prostate gland that occurs commonly in middle aged and older men.
It is important to remember that certain activities can make the PSA level rise, even sky high. The highest PSA levels have been measured in bicycle riders right after a long ride, or right after horseback riding. The bouncing of your bottom on the bike or the horse releases a lot of PSA into the blood, so do not ride your bike or horse to the doctor's office before your test! The prostate exam, where the doctor feels the size of the gland, can raise the PSA level if the doctor massages the gland, something I am careful not to do for routine screening. If I do massage the prostate gland, for example in a man with engorgement of the prostate (a type of prostatitis), I do not measure the PSA level at that time. Ejaculation can also temporarily raise the PSA level a little, so do not get your PSA right after sex. Overnight wait is ok. So, be mindful of what you did, or what was done to you, before getting your PSA level.
The concern about prostate cancer begins at age 50 in most men and that is when the PSA level is often drawn for screening. In African American men, and in men with a family history of prostate cancer, this screening begins at age 40. There is controversy as to whether getting a PSA level is a good idea, and whether it truly saves lives. There are a lot of false positive elevated PSA tests (elevated tests and no cancer present), and the follow-up test is invasive and expensive, an ultrasound exam through the rectum usually with biopsies of the prostate. Also, in older men (over age 70), prostate cancer may grow so slowly that the man may be better off not knowing it is there, since the man will suffer and die from other things. Treatment of prostate cancer is intensive and often reduces the man's sexual function.
If you do choose to get a PSA test, you will be relieved if it comes back low. Mine was 0.5 this year, and any level below 2 is low. One of the most useful things is to measure the change in PSA over time. With age, and with the slow development of benign prostate enlargement, the PSA level goes up very slowly, 1 point or less a year. With prostate cancer, the PSA rises quickly, such as 2 points or more in a year. When a man's PSA level goes from 0.5 to 2.5 in one year, I am concerned even though 2.5 is still considered a normal level. This trajectory, or rate of rise of the PSA, is even more useful than an absolute level. Above 5 is definitely abnormal (not necessarily cancer), but how I interpret a level of 4 is greatly helped by what it was last year. If your PSA is in the "borderline" range of 3-5, it would be useful to follow it more closely, like checking it again in 6 months to see if it is rising.
The PSA is a tricky test to interpret. I hope this information is helpful.
