A normal PSA level is considered to be under 4 nanograms per milliliter (ng/mL) of blood, while a PSA above 10 suggests a high risk of cancer. But there are many exceptions:
Men can have prostate cancer with a PSA less than 4.
A prostate that is inflamed (prostatitis) or enlarged (BPH) can boost PSA levels, yet further testing may show no evidence of cancer.
Some BPH drugs can lower PSA levels, despite the presence of prostate cancer, called a false negative.
If either a PSA or DRE test are abnormal, your doctor will order other tests.