Low PSA: Can Your PSA Level Be Too Low?

Dear Dr. Motola,

If a person has a low PSA can you attribute this to any particular factor or factors? In other words are there any medical reasons for a low PSA? A friend told me that there has to be mitigating factors for this low score.

A low PSA is usually desirable as it will be associated with a lower likelihood of prostate cancer.  Prostate cancer is not always associated with an elevated PSA as tumors that are very high grade may be associated with normal PSA.  This occurs because high-grade tumors are very dissimilar to normal prostate, and as a result lose their ability to secrete PSA. Most often these patients will have very abnormal digital rectal examination.  Patients taking Proscar or Avodart may often have low PSA values. This group of patients needs to have careful scrutiny of the interpretation of their PSA.