There isn't a prostate-specific antigen level that is considered normal or abnormal, explains the National Cancer Institute. Generally, higher PSA levels increase the likelihood of prostate cancer, or if PSA results rise continuously over time, the risk for cancer also increases.
However, studies show that men with PSA levels lower than 4.0 nanograms per milliliter of blood can have prostate cancer, while men with higher levels may not, states the National Cancer Institute. There are many factors that cause PSA levels to rise and fall. Prostate biopsies, urinary tract infections and prostatitis cause a rise in PSA level, while drugs used to treat conditions such as benign prostatic hypertrophy, or BPH, can cause low PSA levels.