The Effect of Transrectal Ultrasonography and Digital Rectal Examination on Serum Free Prostate-Specific Antigen and Percentage of Free Prostate-Specific Antigen Levels

Kim, Dong Suk; Roh, Sang Hue; Lee, Dong Hyeon

Abstract

PURPOSE: To evaluated the effects of transrectal ultrasonography (TRUS) and a digital rectal examination (DRE) on the serum level and percentage of free prostate-specific antigen (PSA).
MATERIALS AND METHODS
Out of 200 patients, aged over 50, with lower urinary tract symptoms, 24 men were excluded from the study due to a past history of severe pain, with prostatitis, a prostate operation, neurologic symptoms, acute obstructive symptoms and finasteride medication, and those showing signs suspicious of prostate cancer on a DRE. Of the remaining 176 patients, only 48 men (mean age 68.9+/-7 years) were willing to participate in the study. Therefore, the level of total PSA, free PSA and percentage of free PSA were determined in this group.
RESULTS
There was no significant difference between the serum total PSA levels before, and 30 minutes after the DRE and TRUS (p>0.05). However, the mean percentage of free PSA (35.3+/-15.3%) after the DRE and TRUS was significantly elevated compared to that before (p<0.01). The mean percentage of free PSA (30.66+/-9.3%) after the DRE and TRUS was significantly elevated compared to that before (20.18+/-8.1%) in the patients with serum PSA levels between 4 and 10ng/ml (p<0.01).
CONCLUSIONS
In our study, the serum free PSA and the percentage of free PSA were significantly elevated by prostate maneuvers, such as DRE and TRUS, however the level of total PSA was unaltered by these maneuvers. Therefore, the collection of blood samples prior to a DRE and TRUS will aid in the diagnosis of prostate cancer. In those with serum PSA levels between 4 and 10ng/ml, the collection of blood samples before a DRE and TRUS are even more important for useful results.