Prostate Specific Antigen (PSA) is a protein produced by both normal and malignant cells of the prostate gland. PSA is primarily found in semen, but a small amount is also present in the blood. The
PSA test measures the level of PSA in a man’s blood and is used primarily to screen for prostate cancer.
The PSA test is a simple blood test. A healthcare provider draws a small amount of blood from a vein in the arm, and the sample is sent to a laboratory to measure the
PSA levels. The results are typically reported as nanograms of PSA per milliliter of blood (ng/mL).
Elevated PSA levels can be indicative of several conditions. While high PSA levels are often associated with
prostate cancer, they can also be caused by benign prostatic hyperplasia (BPH), prostate inflammation (prostatitis), or urinary tract infections. Conversely, low PSA levels are generally considered normal.
Normal PSA levels can vary based on age and other factors. Generally, a PSA level of less than 4 ng/mL is considered normal. However, some doctors use age-adjusted PSA ranges, and other factors such as
ethnicity and family history may also influence what is considered a normal PSA level. Men with PSA levels between 4 and 10 ng/mL have a higher risk of prostate cancer, while levels above 10 ng/mL significantly increase the risk.
The PSA test is not without its
limitations. It can result in false positives, where high PSA levels are not due to cancer, and false negatives, where normal PSA levels overlook existing cancer. Moreover, elevated PSA levels do not distinguish between aggressive and non-aggressive cancer types. As a result, additional tests such as
biopsies, MRI scans, and digital rectal exams (DRE) are often required to confirm a diagnosis.
The decision to undergo PSA screening should be individualized and discussed with a healthcare provider. Generally, the
American Cancer Society recommends that men at average risk start discussing PSA screening at age 50. Men at higher risk, such as African American men and those with a family history of prostate cancer, should consider starting the discussion at age 45.
Yes, certain lifestyle factors can influence PSA levels. Activities such as
ejaculation, vigorous physical activity (especially cycling), and certain medical procedures can temporarily raise PSA levels. Conversely, medications like 5-alpha-reductase inhibitors, used to treat BPH, can lower PSA levels.
Research is ongoing to improve the accuracy of PSA testing. Newer approaches include the use of
PSA velocity (the rate of change in PSA levels over time), PSA density (PSA level adjusted for prostate volume), and the Prostate Health Index (PHI), which combines different PSA forms to provide a more accurate assessment. Additionally, genetic testing and biomarkers are being explored to better identify high-risk individuals.
Conclusion
PSA testing remains a valuable tool in the early detection of prostate cancer, but it is important to understand its
limitations and the need for further diagnostic procedures. Discussing the benefits and risks with a healthcare provider can help make informed decisions about PSA screening.
