PSA antigen is a type of protein released into the blood by the prostate gland in men. Normally, PSA levels are low in healthy men; however, as the prostate enlarges with age PSA levels also rise. PSA levels increase during inflammation of the prostate or prostate cancer. A temporary rise in this protein is also seen after a digital examination of the rectum, sexual activity, or injury.
WHEN IS PSA TEST USUALLY PERFORMED
- Screening test for prostate cancer in men. Medical conditions like benign prostate hyperplasia and prostatitis can also cause an increased PSA levels. Prostate biopsy maybe performed for the confirmation of diagnosis or ruling out prostate cancer.
- PSA test is not used only for diagnosing cancer but along with other tests to determine whether cancer is present.
- PSA test is also used during the active surveillance of prostate cancer. This test helps to check whether the disease is progressing or see whether the patient is responding to the current choice of therapy.
- Many organizations and doctors recommend yearly screening of PSA levels in >50-year-old men.
HOW IS PSA TEST DONE
A blood sample collected intravenously is sent to the laboratory for testing.
INTERPRETING THE PSA TEST
There is no perfect normal value for PSA as it changes with age. Most agree that if you have a PSA level greater than 4 ng/ml, you should get further investigations done. The general rule is that a high value of PSA level is considered more likely to have prostate cancer, and a steady rise in this blood test may also be a sign of cancer.
These are the approximate normal PSA levels according to age:
3 ng/ml for men between the ages 50-59 years
4 ng/ml for men between the ages 60-69 years
5 ng/ml for men over the age of 70 years
If your value of PSA is high without any symptoms, physician may recommend other tests such as digital examination of the rectum to confirm the findings. If PSA levels are still high with no established reason, regular checking of PSA levels and digital examination of rectum is advised.
If there is a steady rise of PSA and a lump has been detected on rectal examination, additional tests will be done such as urine test, transrectal ultrasound, X-rays, or cystoscopy. If prostate cancer is suspected, a biopsy may be needed.
Depending upon your age and family history, your general physician may recommend you to an urologist. If cancer is present, the PSA level gradually rises, which means that small rises in PSA generally occur in localized tumors restricted to the prostate gland. PSA levels of 10 ng/ml are usually localized to the gland. The PSA level and grade of tumor cell can signal that the cancer has gone beyond the prostate gland.
CONDITIONS THAT AFFECT PSA LEVELS AND INTERFERE WITH PSA TEST
- Urine infection
- Vigorous exercise, specially cycling in the 48 hours before the test
- Ejaculation in the 48 hours before the test
- Anal sex or prostate stimulation
- A digital rectal examination might raise your PSA level slightly
- Prostate biopsy 6 weeks before a PSA test
- Other investigations such as bladder or prostate surgery
REGULAR PSA TESTS
Many men might need to have the test regularly over the years after they have had their first PSA test especially, if they are at a high risk of prostate cancer. This test is also used to monitor the prognosis of prostate cancer and check for relapses. Scientists are trying to improve this test so that this antigen will be able to differentiate between cancerous and benign growths of the prostate.