The association between macroprolactin levels and vitamin D status in premenopausal women with macroprolactinemia: a pilot study.

BACKGROUND Macroprolactinemia is a frequent cause of misdiagnosis and mismanagement of patients with elevated prolactin levels. Its pathogenesis and clinical significance are still controversial. METHODS The aim of this study was to investigate the relationship between elevated macroprolactin content and vitamin D status. The study population included 20 premenopausal women with isolated macroprolactinemia, 10 of whom were later treated with vitamin D (2 000 IU daily). Serum prolactin, macroprolactin, 25-hydroxyvitamin D and PTH levels were assessed at baseline and after 4 months of treatment. RESULTS Compared with the control age- and weight-women with normal prolactin levels (n=11), patients with macroprolactinemia were characterized by lower levels of 25-hydroxyvitamin D and slightly higher levels of PTH. Vitamin D administered to patients with macroprolactinemia increased 25-hydroxyvitamin, reduced total prolactin and macroprolactin, as well tended to reduce PTH. The effect of vitamin D on total prolactin and macroprolactin correlated with their baseline values and baseline 25-hydroxyvitamin D levels. CONCLUSIONS The results of our study suggest the association between vitamin D status and elevated macroprolactin levels in premenopausal women.