Effects of intravenous thyrotropin-releasing hormone on urethral closure pressure in females with voiding dysfunction.

Abstract

The aim of this work was to investigate the effects of intravenously administered thyrotropin-releasing hormone (TRH) on the urethral closure pressure in a double-blind, placebo-controlled study. Sixteen female subjects with either bladder outlet obstruction (BOO) or detrusor underactivity were included in the study. Following randomization, 8 subjects (3 BOO, 5 detrusor underactivity) received 200 micrograms of TRH intravenously, and 8 (4 BOO, 4 detrusor underactivity) received saline (placebo). Standard fluid fill urethral pressure profilometry was performed at baseline and 2, 3, 5, 10, 15, and 20 min following TRH injection, measuring functional profile length (FPL), maximum urethral closure pressure (UCP), and closure pressures at the proximal quarter of the FPL (1/4 UCP) and at the distal quarter of the FPL (3/4 UCP). Significant reductions were found in both FPL (p = 0.022) and 3/4 UCP (p = 0.014) in the 'active' group as compared with the 'placebo' group. TRH administration significantly reduces the distal urethral closure pressure. Clarification of the mechanism of action of TRH on the urethra may point the way towards new developments in the management of female voiding dysfunction.