Characterization and assessment of endothelial dysfunction in adolescents with obesity and vitamin D deficiency

Abstract

Background. Obesity and vitamin D deficiency in children are widespread in economically developed countries. Among children with obesity and components of the metabolic syndrome, vitamin D deficiency is more common than in children with a normal body mass index (BMI). The growth of metabolic disorders, atherosclerosis, early onset of type 2 diabetes mellitus lead to fatal vascular accidents in young people, and therefore the search for new ways of early diagnosis of these processes is relevant.
 Aim. To study of the relationship of endothelial dysfunction with vitamin D deficiency, obesity and associated metabolic disorders among adolescents in Saint Petersburg.
 Materials and methods. 5 adolescents aged 1416 years (150.76 years) with primary obesity were examined. Anthropometric parameters were studied: waist circumference, weight, height, calculation of BMI, stage of puberty according to Tanner. Laboratory examination included the following parameters: serum glucose, cholesterol, triglycerides, high density lipoproteins, low density lipoproteins, insulin, 25(OH)D. Atherogenicity index (AI), insulin resistance index (HOMA-IR), vitamin D sufficiency were calculated. Endothelial function was assessed by the value of the reactive hyperemia index (RHI), automatically calculated by the EndoPAT 2000 device (Itamar Medical, Israel).
 Results. All examined patients had abdominal obesity (median BMI 33.5 kg/m2 [30.9; 34.2]) and reduced vitamin D supply (median 25(OH)D 17.2 ng/ml). Hypercholesterolemia and dyslipidemia due to an increase in low density lipoproteins were diagnosed in 1 (20%) case. Dyslipidemia due to a decrease in high density lipoproteins was detected in 3 (60%) patients. An increase in IA was found in 4 (80%) people. Insulin resistance was present in 60% of the examined, the median value of HOMA-IR was 5.6. The median RHI was 1.74 [1.72; 2.13]. Optimum RHI values were observed in 2 (40%) patients; in most (60%) adolescents, the RHI values corresponded to subnormal values and were close to the lower limit of this zone. A significant inverse correlation of RHI with AI was obtained (R=-0.63, p0.05).
 Conclusion. Taking into account the risk factors previously identified in the examined patients (dyslipidemia, insulin resistance, reduced vitamin D supply), endothelial dysfunction in these patients was regarded as a cardiovascular risk factor. A manageable risk factor is a reduced supply of vitamin D, which can be corrected by an additional donation of cholecalciferol.