PSA is also known as prostate specific antigen, and it is commonly used as a way of screening for prostate cancer. The prostate gland is an important part of the male reproductive system and enlarges over time, causing rising PSA levels. PSA levels can also increase due to prostate cancer or because of a condition known as benign prostatic hyperplasia.
Ejaculation within the past 48 hours can cause a sudden rise in PSA levels.
Urinary tract infections can also lead to a rise in a PSA test.
Certain activities, such as bicycle riding, can lead to an increase in PSA levels.
Certain medications--including finasteride (for benign prostatic hypertrophy), cyclophosphamide (a chemotherapy compound) and methotrexate (an immunosupressant)--can also lead to fluctuations in PSA levels.
In some cases, hormones may be prescribed to try to shrink an enlarged prostate. These hormones, in addition to causing the prostate to shrink, will also lower PSA.