Vitamin D, leptin, and body mass index in children and adolescents with hypothalamic dysfunction

Abstract

Deficiency of 25-hydroxyvitamin D (25(OH)D) is considered as a major factor in many adverse health outcomes in children and adolescents. Despite the documented consequences of vitamin D (vit D) deficiency, many unexplained and controversial questions of its relationship with some risk factors for cardiometabolic conditions that often accompany neurohormonal diseases, in particular with markers of excess body weight (BW)/obesity and leptin in hypothalamic dysfunction (HD) in childhood and adolescence. Obesity is one of the leading clinical signs of HD in children and adolescents, which can lead to serious cardiological and metabolic consequences already at a young age, early disability and reduced quality of life of patients. It is advisable to study the relationship between vit. D, body mass index (BMI) and leptin, which are
directly related to the occurrence of the main symptoms of obesity in HD and may affect the development of its complications. There is little research on the relationship between vit. D and leptin, especially among children and adolescents. It should be noted that most studies devoted to the research of the complex relationship between vit. D and leptin were conducted either in healthy individuals or in patients with type 2 diabetes, who suffered or did not suffer from obesity, did not take into account the etiology of obesity and did not study its form. There are practically no such studies in children and adolescents with neuroendocrine pathology, in particular with HD with/without obesity. In Ukraine, no studies have been conducted on the relationship between the content of vit. D, leptin and BMI in the pediatric population with HD. The aim was to investigate the content of serum 25(OH)D in children and adolescents with HD depending on BMI and leptin. Material and methods. 264 children and adolescents (141 boys) with HD aged 10 to 17 years were examined. In patients, the 25(OH)D content was determined with immunochemiluminescent method, leptin level by enzyme immunoassay method, and BMI. Results. Normal BMI<25.0 kg/m2 (18.3-24.9 kg/m2) was found in 18 people (6.82%). Excess BW (BMI=25.0-29.9 kg/m2) was found in 82 patients (31.06%). BMI from 30.0 to 34.9 kg/m2 was found in 84 children (31.82%), BMI from 35.0 to 39.9 kg/m2 – in 51 children (19.32%), BMI ≥40.0 kg/m2 (40.25-56.43 kg/m2) – 29 children (10.98%). It was found that low serum 25(OH)D (vit. D deficiency) is observed in patients with HD even in the presence of excess BW. As BMI increases, the degree of vit. D deficiency increases. In patients with HD and BMI ≥40.0 kg/m2 the lowest 25(OH)D level was observed in relation to this indicator
in the control group and in children with HD with normal BMI (27.06±7.29, 79.3±4.11 and 64.77±7.79 nmol/L, respectively, p<0.05).In the presence of excess BW in patients with HD, the leptin level on average was twice as high as the leptin values in the control group and in patients without excess BW/obesity and was 7.74±0.83 ng/mL (p<0.05). As BMI increases, there is a significant increase in leptin levels. In patients with HD, an inverse relationship was established for leptin and 25(OH)D, an inverse linear relationship between BMI and 25(OH)D level, and a direct linear relationship of moderate strength between BMI and leptin level. Conclusions. In children and adolescents with HD, sufficient serum 25(OH)D levels are associated with normal BMI and leptin levels, while in the presence of excess BW/obesity, vit. D deficiency and high blood leptin levels
are observed. As the degree of vit. D deficiency increases, BMI and leptin levels increas. Children and adolescents with HD and excess
BW/obesity should be considered as a high-risk group of developing cardiovascular pathology and metabolic disorders from an early age. From the moment of diagnosis, it is necessary to monitor BMI, leptin and 25(OH)D levels in order to prevent vit. D deficiency and increase in BW and to carry out appropriate corrections of these indicators.