Relation between vitamin D and adolescents' serum prolactin.

Introduction: To detect whether there is a relation between vitamin D (Vit. D) and adolescents' serum prolactin (PRL) or not.

Material and methods: Hundred and seventy-six adolescent girls were recruited for the current study, which was conducted in West Kazakhstan (Aktobe) over two years. After thorough evaluation, blood samples were taken from adolescents to measure thyroid stimulating hormone (TSH), free thyroxine (T4), PRL, glycosylated hemoglobin and 25(OH)D. The studied adolescents were classified into study group [25(OH)D deficient] and controls [normal 25(OH)D]. The acquired adolescents' variables were analyzed using the Student t-test and Pearson's correlation.

Results: The serum TSH and PRL were statistically higher in the study group than normal controls (3.73 ±1.45 mIU/ml and 47.5 ±7.6 ng/ml vs. 2.67 ±1.0 and 10.8 ±5.1, respectively), (p = 0.0003 and p = 0.0001, respectively). The free T4 was statistically lower in the study group than normal controls (1.4 ±0.6 ng/ml vs. 1.5 ±0.4), (p = 0.0001). Strong negative associations between the serum PRL and 25(OH)D [r = -0.803 (p < 0.00001)], and between the serum PRL and free T4 [r = -0.6959 (p < 0.00001)] were detected in this study. Additionally, there was a strong positive association between the serum PRL and TSH [r = 0.8137 (p < 0.00001)].

Conclusions: A strong negative association between the serum PRL and 25(OH)D and a strong positive association between the serum PRL and TSH were detected in this study. This study recommends further studies to confirm the relation between Vit. D and PRL and screening Vit. D deficient adolescents for PRL and thyroid disorders.