PSA test, free PSA, rate of change,

Ask the Doc: Is My PSA Test Abnormal?

Ask the Doc: Is My PSA Test Abnormal?

I recently had a PSA test. The result was 3.7. The doctor said that this is within the normal range, but I have read that prostate cancer can be present with lower PSA levels. Is there a way I can tell if I have prostate cancer without having a biopsy? J.M.

Dear J.M.: You are correct in stating that prostate cancer can be present even when the PSA level is low. The PSA is a good screening test because it is quite sensitive, meaning that the number of prostate cancer cases that are missed by PSA screening is low. It is, however, not very specific. This means that conditions other than cancer can cause it to be elevated. These would include prostatitis (an inflammation of the gland) and benign prostatic hypertrophy (an enlargement of the gland).

Your result is in a worrisome range, but could be due to prostatic enlargement rather than prostate cancer. The rate at which the PSA rises is a helpful tool in determining what is causing the elevation. When the PSA is less than 4.0 ng/ml it rises approximately 0.75 ng/ml/year when cancer is the cause of the elevation, but only about 0.1 ng/ml/year when non-cancerous enlargement is present. Comparing your current result with that of a previous test is helpful if one is available.

Another helpful tool is a test called a free PSA. This measures the amount of PSA that is not bound to protein. When the PSA is between 3.0 and 4.0 ng/ml a free PSA percentage of 19 or less is suggestive of cancer, while a percentage of 27% or higher points to a benign enlargement of the gland. –Dr. Peterson


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