The effect of hormones on the lower urinary tract

The female genital and lower urinary tracts share a common embryological origin, arising from the urogenital sinus and both are sensitive to the effects of the female sex steroid hormones throughout life. Estrogen is known to have an important role in the function of the lower urinary tract and estrogen and progesterone receptors have been demonstrated in the vagina, urethra, bladder and pelvic floor musculature. In addition estrogen deficiency occurring following the menopause is known to cause atrophic change and may be associated with lower urinary tract symptoms such as frequency, urgency, nocturia, urgency incontinence and recurrent infection. These may also co-exist with symptoms of urogenital atrophy such as dyspareunia, itching, vaginal burning and dryness. Epidemiological studies have implicated estrogen deficiency in the aetiology of lower urinary tract symptoms with 70% of women relating the onset of urinary incontinence to their final menstrual period. Whilst for many years systemic and vaginal estrogen therapy was felt to be beneficial in the treatment of lower urinary and genital tract symptoms this evidence has recently been challenged by large epidemiological studies investigating the use of systemic hormone replacement therapy as primary and secondary prevention of cardiovascular disease and osteoporosis. The aim of this paper is to examine the effect of the sex hormones, estrogen and progesterone, on the lower urinary tract and to review the current evidence regarding the role of systemic and vaginal estrogens in the management of lower urinary tract symptoms and urogenital atrophy.