Explain PSA Blood Tests

Prostate specific-antigen (PSA) is a protein produced by the cells of the prostate. Small amounts of it circulate in the blood. When the prostate forms tumors, these antigens are found at higher levels in the blood. For this reason, a PSA test is used to determine the likelihood of prostate cancer.

Significance

Early screening for cancer can result in treatment before cancer cells metastasize. If a man's PSA levels are high, more tests can be done to determine whether prostate cancer exists.

Procedure

The PSA sample is taken from the blood. The nurse cleans an area on the arm and draws blood from a vein. No preparation is required of the patient.

Considerations

High PSA levels don't always indicate prostate cancer, which is why other tests are run. High PSA levels can be caused by a urinary tract infection or by prostatitis, which is inflammation of the prostate.

Results

A PSA value exceeding 4 nanograms per milliliter is considered high for men. Results below 3 may not lead to further testing. A doctor will make this decision.

Age

Men over 50 should have annual prostate exams. African-Americans and men with a family history of prostate cancer should have annual tests starting at age 40.

References

• University of Maryland: PSA Test Information