Vitamin D, vitamin D-binding protein and parathyroid hormone in children and adolescents with obesity and dysfunction of the hypothalamus

Abstract

According to modern concepts, hypothalamic dysfunction (HD) is a neuroendocrine syndrome caused by dysfunction of the hypothalamic-pituitary system and is manifested mainly by hormonal and metabolic disorders and vegetative-vascular disorders. Adolescent obesity, associated in many cases with HD, and with a high risk of developing vitamin D (vitD) deficiency. Obesity in association with HD and vitD deficiency causes serious health problems, and the vitD/parathyroid hormone (PTH) axis plays a potential role in their etiopathogenesis. Purpose - to study the relationship between vitD, vitamin D-binding protein (VDBP) and parathyroid hormone levels in adolescents with obesity against the background of HD. Materials and methods. The serum level of vitD was determined by the immunochemiluminescence method on microparticles (Abbott, USA) in 87 children and adolescents with overweight/obesity against the background of HD aged 10-16 years. The VDBP level was determined using enzyme-linked immunospecific assay (ELISA) with commercial standard kit Elabsciense Biotechnology Co., Ltd (USA). The PTH level - by immunochemiluminescence assay with commercial standard kit Monobind (USA). Results. Insufficiency of vitD was noted in 32.2%, deficiency - in 56.3% of patients. The severity of obesity was associated with the levels of vitD: a decrease in the level of vitD in children and adolescents with overweight (69.30±5.14 nmol/l) and the I stage of obesity (52.60±4.17 nmol/l), a significant deficiency of vitD in persons with the II and III stages of obesity (36.20±3.75 nmol/l, 23.10±3.12 nmol/l respectively). A significant decrease of vitD level in obese patients was accompanied by a significant increase of the PTH level. In the III stage of obesity, the level of PTH was twice as high as the level of PTH in practically healthy children and adolescents with normal MT and in patients with excess body weight (p<0.05). With a body mass index (BMI) >30 kg/m2, there was a significant decrease in the content of vitD, associated with a significant increase in the level of PTH and a sharp decrease in the level of VDBP. The level of VDBP had a positive correlation with vitD level and a negative relationship with BMI. A significant decrease in the content of VDBP (58.71±18.43 ng/ml)) was established in comparison with a group of practically healthy children and adolescents with normal body weight (141.65±25.34 ng/ml) (р<0.05). Conclusions. The results indicate the presence of certain changes in the PTH/vitD/VDBP axis in children and adolescents with excess body weight/obesity against the background of HD, which are an integral part of the complex manifestation of the disease. Maintaining an adequate vitD status can contribute to the prevention of such disorders. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.