Hormone Replacement Therapy and Urinary Incontinence
Hormone Replacement Therapy and Urinary Incontinence: What Every Gynecologist Needs to Know
A Paradoxical Relationship Between Hormone Replacement Therapy and Urinary Incontinence
The relationship between hormone replacement therapy (HRT) and urinary incontinence poses an important clinical challenge. It appears that the route of administration determines the effect on urinary symptoms. Understanding the differences between systemic and local vaginal therapy is essential for optimal care of menopausal women.
Systemic Hormone Therapy - Worsening Urinary Incontinence
The large WHI (Women's Health Initiative) studies have consistently shown that systemic hormone therapy, whether estrogen alone or in combination with progesterone, increases the risk of new urinary incontinence and worsens existing symptoms. In the WHI study, women who received estrogen alone had an increase of 885 new cases of urinary incontinence per 10,000 women over one year. A Cochrane systematic review of nearly 20,000 women found that systemic treatment (oral pills) led to a worsening of urinary incontinence (RR 1.32, 95% CI 1.17-1.48) compared with placebo.
The risk applies to all types of urinary incontinence - stress incontinence, urge incontinence and mixed incontinence. The exact mechanism is not entirely clear, but may include changes in the collagen of pelvic floor tissues and uterine ligaments, effects on detrusor muscle tone, or changes in connective tissue metabolism.
Vaginal estrogen - improvement of urinary symptoms
In contrast to systemic treatment, topical vaginal estrogen (creams, suppositories, etc.) improves urinary symptoms in postmenopausal women. A 2023 systematic review found that vaginal estrogen improves dysuria, frequency, urgency, stress and urge incontinence, and reduces recurrent urinary tract infections. A Cochrane meta-analysis showed improvement in urinary incontinence (RR 0.74, 95% CI 0.64-0.86) with topical treatment, with a reduction of 1-2 micturition events per day.
Benefits of vaginal estrogen include restoration of the vaginal epithelium, restoration of normal vaginal flora, increased moisture and secretions, and restoration of acidic vaginal pH. It is important to note that serum estradiol levels remain in the postmenopausal range with most vaginal preparations.
Clinical recommendations
Avoid systemic treatment for urinary incontinence: Systemic HRT should not be used to treat urinary incontinence. Women with existing urinary incontinence who require systemic HRT for other reasons (hot flashes, osteoporosis) should be aware of the risk of worsening.
Use of vaginal estrogen: For women with GSM (Genitourinary Syndrome of Menopause) symptoms that include urinary symptoms, vaginal estrogen is an effective and safe treatment. The various preparations (creams, suppositories, etc.) have shown similar efficacy. Vaginal therapy is also safe for breast cancer survivors.
No need for progesterone: Based on one-year safety data, progesterone is not needed to protect the endometrium with the use of low-dose vaginal estrogen. However, postmenopausal bleeding requires evaluation.
Safety: Vaginal estrogen has not been shown to increase the risk of breast cancer, endometrial cancer, coronary heart disease, stroke, or venous thromboembolism, but carries the same warning as systemic HRT.
Combination with other treatments: A small study showed that physiotherapy with pelvic floor muscle training (PFMT) was more effective than topical estrogen for urinary incontinence (RR 2.30), so a combination of treatments may be optimal.
Summary
The association between HRT and urinary incontinence depends on the route of administration. Systemic therapy worsens or causes new urinary incontinence, whereas vaginal estrogen improves urinary symptoms and is a first-line treatment for women with GSM. This distinction is essential for appropriate patient counseling and selection of appropriate treatment.
