25-hydroxyvitamin D Correlation with Prolactin Levels and Adenoma Size in Female Patients with Newly Diagnosed Prolactin Secreting Adenoma

Objective: The present research explored the relationship of vitamin D status with prolactin levels and adenoma size in female patients with newly diagnosed prolactinoma and determination of hypovitaminosis D prevalence among female patients with prolactinoma. Patients and Methods: We enrolled 67 female patients with newly diagnosed prolactinoma (41 with micro adenoma and 26 with macro adenoma) in this case-control study at the time of presentation. We selected 45 female subjects as a control group who were matched according to age, weight, height, body mass index and waist circumference. We investigated 25-hydroxyvitamin D, the major circulating form of vitamin D. Results: Prolactinoma patients had significantly lower 25-hydroxyvitamin D levels in comparison with control subjects. Also, macroadenoma patients showed significantly lower 25-hydroxyvitamin D levels as compared to microadenomoa patients. By contrast, microadenoma patients had nonsignificant lower 25-hydroxyvitamin D levels in comparison with control subjects. Furthermore, we found prolactinoma patients with 25-hydroxyvitamin D >20.00 ng/ml showing significant differences in the prolactin levels and adenoma size when compared with those who had 25- hydroxyvitamin D <20.00 ng/ml. In regression analysis, 25-hydroxyvitamin D level was a significant predictor of adenoma size in patients diagnosed with prolactinoma. Conclusion: Female patients with prolactinoma have lower vitamin D levels and have higher prevalence of vitamin D insufficiency and deficiency among prolactinoma patients when compared with normal subjects. Also vitamin D deficiency in prolactinoma patients associated with larger adenoma size and higher prolactin level. Finally, 25-hydroxyvitamin D level was a statistically significant predictor of prolactinoma size but not prolactin levels.