U-Shaped Association Between Serum 25-hydroxyvitamin D concentrations and Urinary Leakage Among Adult Females Aged 45 Years and Over in the United States: A Cross-Sectional Study

Background: The relationship between serum vitamin D status and urinary leakage (UL) among middle-aged females remains to be further studied. In this study, we aimed to evaluate the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with UL among American females ages 45 years and over. Methods We used seven cycles of the National Health and Nutrition Examination Survey (NHANES) with self-report UL data. A total of 9525 women, 45 years and older, were enrolled in this study. Univariate and multivariate logistic regression models and the smooth curve fitting were used to analyze the association between clinical UL and serum 25-hydroxyvitamin D [25(OH)D] concentrations. Results We observed a non-linear relationship between serum 25(OH)D concentrations and clinical UL. We found that when serum 25(OH)D concentration was higher than the inflection point 63.5, there was a positive correlation between serum 25(OH)D concentrations and clinical UL ([OR]: 1.007, 95%CI: 1.005–1.009, P < 0.01). However, when serum 25(OH)D concentration was lower than the inflection point 63.5, there was a negative correlation between serum 25(OH)D concentrations and clinical UL ([OR]: 0.993, 95%CI: 0.989–0.996, P < 0.01). Conclusions The association between serum vitamin D and the risk of UL followed an U-shaped relation among US middle-aged females, with an inflection point at 63.5 nmol/L serum 25(OH)D concentrations.