Association Between Serum 25-Hydroxyvitamin D Levels and Clinical Characteristics of Adenomyosis: A Case-Control Study

Background Adenomyosis is a chronic gynecological condition characterized by the presence of endometrial glands and stroma within the myometrium, resulting in dysmenorrhea, menorrhagia, and infertility. Objectives This study was designed to investigate the relationship between serum 25-hydroxyvitamin D (25(OH)D) levels and adenomyosis and explore whether vitamin D deficiency is associated with the clinical characteristics of clinical symptoms. Methods This case-control study included 177 women with adenomyosis and 178 age-matched healthy controls. Demographic and clinical data were collected, including age, BMI, parity, VAS pain scores, serum CA125 levels, and uterine volume. Serum 25(OH)D levels were measured and analyzed. Univariate and multivariate regression models were used to assess associations between vitamin D levels and disease parameters. Results Women with adenomyosis had significantly lower serum 25(OH)D levels compared to controls (12.14 ± 4.65 ng/mL vs. 14.13 ± 5.02 ng/mL, p = 0.0001). They also had significantly higher VAS pain scores (7.17 ± 2.13 vs. 3.07 ± 1.98, p < 0.0001), larger uterine volumes (261.98 ± 81.99 cm³ vs. 110.98 ± 15.67 cm³, p < 0.0001), and elevated CA125 levels (70.32 ± 27.02 U/mL vs. 23.18 ± 6.09 U/mL, p < 0.0001). Multivariate linear regression showed that lower 25(OH)D levels were significantly associated with greater uterine volume and higher VAS pain scores. No significant association was observed between vitamin D and CA125 levels. Conclusion lower serum 25(OH)D levels were observed in adenomyosis patients and lower vitamin D levels is associated with increased pain severity and larger uterine volume in adenomyosis patients.