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.