Hyperleptinemia and leptino-resistance in patients with hypertension in case of metabolic syndrome

Abstract

Introduction: Metabolic syndrome (MS) is found in 20-25% of the population, in 15% of Europeans and in 23% of Americans. High blood pressure (HBP) is often associated with anthropometric and metabolic disorders, including abdominal obesity (AO), insulin resistance (IR), and other disorders of the MS. The effect of leptin on blood pressure (BP) indicates that leptin plays an important role in the BP control, it reflects the body fat mass (FM), which produces the leptin and is importantly increased in case of obesity. Hyperleptinemia (HL) may be associated with leptino-resistance (LR), usually in case of obesity. Purpose of the study: The purpose of the research was to assess the role of leptin metabolism, hyperleptinemia and leptino-resistance in hypertensive patients in case of metabolic syndrome. Material and methods: The study included 294 patients. The main criterion for selection was the HBP of Ist and IInd degree. The selection of the groups of patients with and without MS for further investigations was carried out according to the classification criteria of the NCEP/ATP III (2005). Leptin concentration was determined by immunoenzymatic method. The normal blood levels of leptin in women - from 4.1 to 25 ng/ml, in males - from 1.2 to 9.5 ng/ml. Results and discussions: The men’s average leptin levels in the analyzed group were found to be significantly lower than in women (17.51 ± 1.36 ng/ml vs. 29.33 ± 2.14 ng/ml, p<0.01). Spearman correlation analysis showed a direct dependence in both groups of patients between leptin levels and BMI (Body Mass Index). We also observed that leptin level is higher in MS patients, presenting in all cases IR and disturbance of insulin sensitivity of the tissues. After determining the secretory activity of adipose tissue (AT) by leptin level, and after the investigation of basal insulin (BI) in patients with MS, we obtained: 1) hyperleptinemia - 83.3 % of patients (average concentration of leptin in women - 41,58 ± 5,12 ng/ml, and in men - 29.02 ± 3.68 ng/ml with normal values from 4.1 to 25 ng/ml), which suggests the presence of a pronounced LR in patients with MS and 2) basal hyperinsulinemia in 67 % of patients ( the average BI was 18.12 ± 4.03 IV pUI/ml). All the patients (100%) presented an increased HOM Air index (the average index was 4.04 ± 0.95 conventional unities, normal values < 2.5), which corresponds to an elevated IR in these patients. Therefore, the patients that were included in our study, in addition to the MS signs, manifested important changes of AT secretory activity with associated LR and IR. The Spearman correlation analysis showed a statistically significant positive correlation between leptin level in patient with MS and body weight (r=0.31, p<0.01), abdominal circumference (r=0.38, p<0.001), and BMI (r=0.69, p< 0.0001). These correlations can be related to the HL, with secondary increased body weight. Conclusions: Leptin and hyperleptinemia are crucial factors in the various interactions of metabolic alterations of MS. Hyperleptinemia, as manifestation of peripheral leptino-resistance, was determined in 83.3 % of hypertensive patients with metabolic syndrome, and presented a direct correlation with the increasing of degree of obesity. The relationship between the body mass index, hyperleptinemia and hyperinsulinemia reflects its key role in the pathogenesis of insulin resistance in metabolic syndrome.