PSA is a protein that comes from prostatic tissue and its level can be checked via a blood test. It is useful in telling doctors which treatments may benefit patients with benign and malignant prostate diseases, who needs to be examined further for prostate cancer, and for monitoring treatment for prostate cancer.
A PSA test may detect prostate cancer at an early stage when it can be detected by no other means and even when there are no other symptoms at all. Conversely, not all men who have a raised PSA level will have prostate cancer. If prostate cancer is diagnosed, the PSA test can be very valuable in monitoring the condition as well as the response to all forms of treatment.
The test works by measuring the amount of the protein in the blood. The level of PSA in the blood can be raised by PSA finding its way out of the prostate into the blood stream, through the prostate walls becoming weakened through diseases, particularly prostate cancer. The greater the leakage, the greater the amount of PSA can reach the bloodstream. An elevated level, however, can be for a number of reasons rather than always necessarily being an indicator of prostate cancer. The level can go up due to a number of different conditions including:
Age
Benign prostate growths
Malignant prostate growths
Urinary tract infections (water infections, see prostatitis risk factors)
Inspections of the bladder using cystoscopes
Significant levels of cycling (more than 10 miles/day on a regular basis)
Sex
The last 5 only raise PSA for a short period of time and it will go back to its more normal level when the infection is treated or after a period of abstinence. As PSA goes up with age, most doctors now use age-specific PSA ranges, as a PSA that is elevated in a 45 year old man may be normal in a 75 year old man.
The normal PSA levels are:
Age 40-49 years ~ 2.5 ngms/ml
Age 50-69 years ~ 0-3 ngms/ml
Age 70+ years ~ 0-5 ngms/ml
PSA circulates in 2 forms in the blood. One type is linked to a second protein, while the other is 'free'. As part of the PSA test, the amount of 'free' PSA, which is not linked, may also be measured. This is because a lower amount of 'free' PSA may indicate prostate cancer and a higher amount is more likely to indicate benign prostate growth. A percentage level of 'free' PSA below 18 is more likely to indicate prostate cancer.
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