The Influence of Prostate Volume on the Serum Prostate-specific Antigen Levels and the Percentage of the Free Prostate-specific Antigen Levels during Finasteride Medication

Purpose: Little is known about the effect of the prostate volume on the free prostate-specific antigen (PSA) level and the percent of the free PSA level with administering finasteride medication. We studied the effect of finasteride therapy on the levels of serum PSA, the free PSA and the percentage of free PSA according to the prostate volume. Materials and Methods: Patients with lower urinary tract symptoms (LUTS) and benign prostatic hyperplasia (BPH) and who were over 50 years old were treated with finasteride 5mg for 6 months. Male patients with a PSA level between 3.5ng/ml and 15ng/ml were included and these patients were biopsied. α-blockers were prescribed to treat them for LUTS. The serum levels of the total PSA and free PSA were measured at baseline and after 6 months. We analyzed the changes of PSA and fre-PSA before and after finasteride administration. We also analyzed the patients' changes based on the prostate volume. Results: The analysis included 44 patients with a mean age of 71.7 years, a baseline prostate volume of 56.0cc and a baseline total PSA level of 6.74ng/ml. The total PSA and free PSA levels declined from 6.74ng/ml and 2.57ng/ml at baseline to 3.83ng/ml and 1.45ng/ml after 6 months of treatment, respectively (p<0.05). The mean percent free PSA was not significantly altered by finasteride treatment. Those patients with a small prostate volume showed larger decrements in the PSA and free PSA than did the patients with a large prostate volume, but the prostate volume at baseline did not affect the percent free PSA levels. Conclusions: It is debatable that the application of the 'double's rule' without considering the volume of the prostate is appropriate for the treatment of patients who are taking finasteride medication. (Korean J Urol 2007;48:1242-1246) 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏