Vitamin D Status and Reproductive Hormonal Profiles in Early Versus Physiological Menopause: A Comparative Observational Study

Background: An early menopause (by definition, menopause that occurs at a woman’s age 40 through 45) is often associated with certain changes in the body that can result in risks for health-related conditions, an extended period later. Thus, scientists have begun examining how vitamin D has been suggested to be associated with endocrine function regulating both hormones and reproductive function during this time. However, it is not yet clear as to whether or not vitamin D provides any benefit to women who have experienced an early menopause. Material and Methods: The data was collected from 272 women in this retrospective, observational study at The County Hospital, Department of Obstetrics and Gynecology, Arad. The method of grouping the sample included two stratifications into early and physiological menopause categories based on amenorrhoea for a minimum of 12 consecutive months. 25-hydroxyvitamin D (25(OH)D) levels were classified into three categories: deficiency (<20 ng/mL), insufficiency (21–29 ng/mL), or adequacy (≥30 ng/mL). Estradiol, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) hormone parameters were measured using standard immunoassays. The analysis employed correlation and regression to evaluate potential relationships between 25(OH)D levels and hormone parameters. Results: A significant proportion of the study group had a vitamin D deficiency. This was supported by the fact that only 24.27% of women were identified as having adequate levels of vitamin D, while the rest (62.03%) did not. Women in the early menopause group had a statistically significant negative relationship between estradiol and FSH (i.e., r = −0.29, p = 0.0016), as well as between progesterone and LH (i.e., r = −0.207, p = 0.026). There was not a statistically significant relationship between total sample vitamin D and estradiol (i.e., r = −0.038, p = 0.686) nor between vitamin D and progesterone (i.e., r = 0.031, p = 0.744). Women with vitamin D blood levels of 30 ng/mL or more showed a strong negative relationship between vitamin D and estradiol (r = −0.780; p = 0.0016) and a moderate positive relationship with progesterone (r = 0.534; p = 0.0104). However, these relationships were inconsistent in other groups. All group comparative analyses showed that women in the early menopause group had much lower estradiol levels than those in the physiological menopause group, regardless of whether they were classified based on their vitamin D levels (p < 0.0001). Conclusions: Women experiencing early or physiological menopause are at risk of having low vitamin D levels. However, our study results do not show a consistent relationship between serum 25(OH)D concentrations and serum estradiol or progesterone concentrations among the study population, suggesting that vitamin D is not a major factor influencing hormonal changes during menopause. These findings were inconsistent across analyses and should be interpreted cautiously. Overall, the results do not support a significant association between serum 25(OH)D concentrations and reproductive hormone levels in our study population.