There is no specific normal or abnormal level of PSA in the blood, according to the National Cancer Institute. In general, the higher a man's PSA level, the more likely it is that he has prostate cancer.
A continuous rise in a man's PSA level over time may be a sign of potential prostate cancer, explains the National Cancer Institute. Although there is no specific normal or abnormal level of PSA in the blood, traditionally doctors have considered PSA levels of 4.0 nanograms per milliliter and lower as normal. Recent studies have shown that it is possible that some men with PSA levels below 4.0 nanograms per milliliter have prostate cancer as well.
Various factors can cause a man's PSA level to fluctuate, including presence of prostatitis or a urinary tract infection, notes the National Cancer Institute. Prostate biopsies and prostate surgery also increase PSA levels. Drugs including finasteride and dutasteride, which are used to treat benign prostatic hyperplasia, or BPH, lower a man's PSA level.
A complicating factor is that studies to establish normal ranges of PSA in men have been conducted primarily in the white population, states the National Cancer Institute. Although experts vary on the topic, there is no consensus regarding the optimal PSA threshold for the recommendation of a prostate biopsy for men of any racial or ethnic group.