Vitamin D and uterine leiomyoma among a sample of US women: Findings from NHANES, 2001–2006

• We tested the relationship between Vitamin D exposure and uterine leiomyoma.
• No relationship was found in population-based analyses.
• We used self-reported outcomes, so misclassification may explain the null results.
• An analysis correcting for misclassification suggests an association in white women.

Scientific understanding of the etiology of uterine leiomyomata (UL) remains incomplete, but recent investigations have suggested an association between low Vitamin D and UL risk. In this study, we conducted a cross-sectional analysis of Vitamin D exposure, measured using serum levels of 25(OH)D (a Vitamin D metabolite), and self-reported UL diagnosis among 3590 women aged 20–54 in the National Health and Nutrition Examination Survey (NHANES 2001–2006). Multivariate logistic regression models comparing each quartile of 25(OH)D to the lowest quartile indicated no relationship between 25(OH)D and odds of UL in the whole population (Ptrend = 0.37), or in sensitivity analyses. However, a probabilistic analysis correcting outcome misclassification indicated that insufficient 25(OH)D was associated with UL in white (Odds ratio (OR) median estimate: 2.17; 2.5, 97.5 percentiles: (1.26, 23.47)), but not black women (OR median estimate: 1.70; 2.5, 97.5 percentiles: (0.89, 3.51)), suggesting misclassification may have driven some of the null findings.