Along with the digital rectal exam (or DRE), in which a physician inserts a gloved finger into the rectum to examine the prostate for irregularities, a PSA test is the leading method of screening for prostate cancer. A PSA test can help catch the disease at an early stage when treatment is thought to be more effective and potentially has fewer side effects.

What is PSA?

PSA, or prostate specific antigen, is a protein produced by the prostate and found mostly in semen, with very small amounts released into the bloodstream. When there’s a problem with the prostate—such as the development and growth of prostate cancer—more PSA is released. Rising PSA eventually reaches a level where it can be easily detected by a blood test.

For more information on rising PSA, download or order a copy of the Prostate Cancer Patient Guide.

What is the PSA Test?

During a PSA test, a small amount of blood is drawn from the arm, and the level of PSA, a protein produced by the prostate (not prostrate), is measured.

Doctors look at the overall level of PSA, as well as the rate at which it is rising (velocity). As the PSA number goes up, the chance that cancer is present increases. Men whose levels go above 3 or 4 are often recommended to undergo a biopsy; however, this PSA level does not mean that prostate cancer is definitely there, and some cancers be present even when PSA levels are lower.

Remember that assessment of PSA must also take into account:

  • The patient’s age
  • Prostate size
  • Previous PSA tests
  • Other medical conditions, such as BPH or prostatitis
  • Medications that may artificially lower PSA, such as finasteride (Proscar or Propecia) or dutasteride (Avodart)
  • Infections and procedures involving the urinary tract that can elevate the PSA

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