What Are the Causes of High Levels in a PSA Reading?

Prostate cancer is one of the most common forms of cancer in men. Once detected only by a digital rectal exam, or DRE, most diagnoses now involve testing for prostate-specific antigen, or PSA, a substance produced by the prostate. Most doctors are reluctant to diagnose on the basis of a single test, because prostate cancer is only one of the factors that can cause elevated PSA levels.

Specificity

• Prostate cancer is a known cause of high PSA readings. The problem with the test is what doctors refer to as "specificity" -- prostate cancer means a high PSA, but a high PSA does not always mean cancer. A secondary analysis, comparing "free" PSA -- not bound up with a protein -- to "bound" PSA, improves the accuracy of the test. The lower the percentage of free PSA, the greater the likelihood of a cancer diagnosis. Aside from cancer, several other factors can increase PSA.

Age

• An increase in PSA is one symptom of aging in males, as the prostate's size normally increases over time. The Family Practice Notebook quotes normal PSA values as under 2.5 for white men between 40 and 50, while for men between 70 and 80 years of age that number jumps to 6.5. PSA figures are always expressed in nanograms per milliliter, or ng/ml.

Benign Conditions or Sexual Activity

• Many benign medical conditions may cause high PSA readings. Benign prostatic hyperplasia, prostatitis and simple infections are common causes of elevated readings, and some physicians prescribe a course of antibiotics before re-testing in order to remove the latter possibility. Men are urged to avoid any sexual activity prior to giving the blood sample for a PSA test, as ejaculation may increase PSA levels for up to 48 hours.

Medical Procedures

• Some medical procedures increase PSA levels in the blood. These include digital rectal examinations, prostate massage and catheterization. Since DREs and PSA tests are part of the same diagnostic process, doctors have learned to draw the blood sample before performing the rectal examination. Cystoscopies, a diagnostic process in which the ureter and bladder are visually examined with a lighted tube, can have the same effect.