Sexual Function and Depressive Symptoms in Metformin-Treated Women with Drug-Induced Hyperprolactinemia and Different Vitamin D Status: A Pilot Study.

Background

Elevated prolactin levels are associated with disturbances in female sexual function. While long-term therapy with dopamine agonists has been shown to improve these disturbances, the therapeutic benefits appear to be reduced in the presence of vitamin D deficiency or insufficiency. Therefore, the present study aimed to examine whether vitamin D status modulates the effects of metformin-a medication with less pronounced prolactin-lowering properties-on sexual function and depressive symptoms.

Methods

The study cohort comprised three groups of reproductive-age women with drug-induced hyperprolactinemia and prediabetes, matched for age, glycated hemoglobin, and prolactin concentrations. Group I included 25 women with normal vitamin D status who were not receiving vitamin D supplementation. Group II consisted of 25 women with vitamin D deficiency or insufficiency that was adequately corrected through supplementation, while group III included 25 women with untreated vitamin D deficiency or insufficiency. All participants received metformin throughout the six-month study period. Female sexual function and depressive symptoms were assessed before and after metformin therapy using the Female Sexual Function Index (FSFI) and the Beck Depression Inventory-II (BDI-II), respectively. Additional outcome measures included plasma 25-hydroxyvitamin D, fasting plasma glucose, glycated hemoglobin (HbA1c), the homeostatic model assessment of insulin resistance (HOMA-IR), prolactin, gonadotropins, and sex hormones.

Results

Improvements in glucose homeostasis were observed across all groups; however, these changes were more pronounced in groups I and II than in group III. Reductions in prolactin concentrations (total and monomeric), accompanied by increases in gonadotropins, estradiol, and testosterone, were observed exclusively in women with normal vitamin D status. In groups I and II, metformin therapy resulted in significant improvements in total FSFI scores as well as in all individual domain scores. In contrast, in group III, the effects of metformin were limited to increases in the domain scores for lubrication and sexual satisfaction. Improvements in sexual function were positively associated with baseline 25-hydroxyvitamin D levels, reductions in prolactin concentrations, and, to a lesser extent, treatment-related changes in HbA1c and increases in testosterone. A treatment-induced reduction in total BDI-II scores was observed only among women with normal vitamin D status.

Conclusions

Low vitamin D status diminishes the beneficial effects of metformin on sexual function and depressive symptoms in reproductive-age women with iatrogenic hyperprolactinemia.