What is PSA?

May 5, 2007

PSA (Prostate Specific Antigen) is a protein secreted by the healthy prostate in the seminal fluid. Normally, only very small amounts of this protein are released in the bloodstream.
A diseased prostate will produce and release in the blood large quantities of this protein. The blood test is identifying the level of PSA and can be used in early detection of prostate cancer as well as to monitor men with a history of prostate cancer.
PSA levels alone do not give doctors enough information to distinguish between benign prostate conditions and cancer. So nobody is able to tell you: “You have cancer” or “You certainly don’t have cancer” only by knowing your PSA levels. Also, an elevated PSA level in a patient with a history of prostate cancer does not always mean the cancer has come back.
Anyway, if you had a PSA, go and talk with your doctor about the results. He and only he will know if you need further tests.
I will give you a short diagram about how you should interpret your PSA test, but I have to tell you that this data are not replacing a doctor appointment.

PSA Level	Probability of cancer
0-2 ng/mL	1%
2-4 ng/mL	15%
4-10 ng/mL	25%
>10 ng/mL	>50%

There are other conditions than cancer that can raise PSA level like: Benign prostate enlargement, urinary infection, prostatitis or a biopsy of the prostate can cause large rises while small rises can be caused by ejaculation and even bicycle riding. The level of PSA also increases with age and it’s higher in African American men.
If you ask me who should have a PSA test, I will tell you this is your doctor’s decision. Anyway, I recommend a test every year for: all men over 50 and men over 40 with blood relatives who have had prostate cancer or in high-risk groups, such as African Americans.

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