Most authorities agree that if you have a PSA greater than 4 ng/ml, you should have further investigations. Some suggest that if your PSA is greater than the 'normal for age' range shown in Table 1, or if it is rising rapidly, it should be investigated.
Depending on your age and family history, your doctor may then refer you directly to a Urologist, or may repeat the test before referring you for further investigation.
If cancer is present, the level of PSA in the blood rises as the tumour grows. This means that small rises in PSA are found in association with small tumours which may be still confined to the prostate gland (localised). PSA levels of 10ng/ml or less have the best chance of being localised 3. The PSA level and the cancerous characteristics of the tumour cells themselves (called "grade") can indicate the risk that a tumour has grown beyond the prostate.
If cancer is present, the rate at which the PSA level increases over a series of tests (called PSA velocity) also gives information about the risk that cancer will recur after treatment
