A normal PSA level is considered to be 4.0 nanograms per milliliter of blood. Doctors often recommend a prostate biopsy to determine whether prostate cancer is present if a man has a PSA level above 4.0 nanograms per milliliter, according to the National Cancer Institute.
The PSA test measures the blood level of prostate-specific antigen, a protein produced by the prostate gland. The higher a man’s PSA level, the more likelihood there is that he has prostate cancer. More recent studies, however, show that some men with PSA levels below 4.0 nanograms per milliliter have prostate cancer, and many men with higher levels do not have prostate cancer, explains the National Cancer Institute.
Other factors can cause a PSA level to fluctuate. These include an enlarged prostate, prostatitis or inflammation of the gland, a urinary tract infection, recent procedures and biopsies of the bladder or prostate, and placement of a catheter tube into the bladder to drain urine, as stated by MedlinePlus.