Sex Hormone–Binding Globulin in Postmenopausal Women With Urinary Incontinence

Importance Vaginal estrogen may improve urgency urinary incontinence (UUI) while systemic estrogen may worsen urinary incontinence (UI). Low testosterone is linked to UI. Sex hormone–binding globulin (SHBG) binds circulating estrogen and testosterone, reducing bioavailability and potentially affecting genitourinary function by limiting local hormone availability. Objectives The objectives of this study were to investigate the relationship between UI and SHBG levels, bioavailable estrogen, and testosterone in postmenopausal women. We hypothesized that women with higher SHBG levels would be more likely to have urgency and stress urinary incontinence. Study Design This was a cross-sectional analysis of National Health and Nutrition Examination Survey (NHANES) data from 2013 to 2016, including serum measurements of SHBG, estradiol, and testosterone. Bioavailable hormones were calculated using hormone/SHBG ratios. The analysis examined hormone levels in women with urgency, stress, and mixed incontinence. Descriptive statistics, weighted analysis of covariance, and weighted logistic regression were performed. Results Among 2,318 postmenopausal women with SHBG measurements, 1,522 (65.7%) reported stress or urgency UI. After adjusting for age, body mass index, race, smoking status, and vaginal deliveries, women with UUI had significantly higher SHBG than those without UUI ( P =0.0214). Women with UUI had significantly lower free estrogen ( P =0.0433) and free testosterone ( P =0.0025). The odds of experiencing UUI increased 1.37-fold when SHBG was ≥65 nmol/L ( P =0.0134). Conclusion Higher SHBG levels and lower free estrogen and testosterone are associated with UUI in postmenopausal women, suggesting bioavailable hormones play crucial roles in maintaining genitourinary tract function.