PSA is a test to determine the amt of Prostate Specific Antigen in your blood. Saw Palmetto is supposed to block DHT I think??? Or maybe it blocks the conversion of test to DHT?? In any event it may give you a false value on the test. Below 4 is ok, the lower the better. Above 4, and they need to take further invasive action ....US, biopsy, chemo, radiation, hospice, death