Lipid metabolism in non-alcoholic fatty liver disease in patients with different body weights in mid-mountain conditions

Aim. To study the peculiarities of lipid metabolism disorders in non-alcoholic fatty liver disease in lean and obese patients in medium altitude conditions.

Materials and methods. The study was carried out within the framework of the project “Etiopathogenetic features and rates of development of non-alcoholic fatty liver disease (NAFLD) in the conditions of Kyrgyzstan” (№ of state registration MHN/TZ-2020-3). An open comparative study of patients with two forms of NAFLD: fatty liver and non-alcoholic steatohepatitis (n=236) living in low mountains (Bishkek, altitude above sea level – 750–800 m; n=111) and middle mountains (At-Bashy district , Naryn region, height above sea level – 2046–2300 m; n=125) Kyrgyzstan. The average age of the patients was 55.7±0.95 years. Given that genetic factors may play a role in the development of NAFLD, we analyzed a population represented only by ethnic Kyrgyz. Patients in each group were divided into lean (BMI≤23) and obese (BMI>23) groups. To determine physical activity, a physical activity questionnaire was used, which was compiled on the basis of the materials of the International Physical Activity Prevalence Study www.ipaq.ki.se. Physical examination included measurement of anthropometric parameters (height, body weight, waist circumference), calculation of body mass index (BMI), skeletal muscle mass index (SMM), percentage of body fat. According to the grades of the WHO, the degree of obesity was assessed by BMI for Asians. Blood samples were taken for research in the morning on an empty stomach after at least 12 hours of fasting. The following indicators were determined: glucose, lipid spectrum (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides), alanine aminotransferase (ALT), aspartate aminotransferase (AST) levels. The BARD scale was used as a predictor for assessing the development of liver fibrosis in patients with NAFLD. The scoring system included three variables: BMI, AST/ALT, and the presence of DM 2. The diagnosis of NAFLD made on the basis of history, laboratory tests, ultrasound examination of the liver, and exclusion of other liver diseases. The results were analyzed using the SPSS 16.0 statistical software package for Windows. A p-value<0.05 was considered statistically significant at the 95% confidence level.

Results. It was found that the inhabitants of the middle mountains with NAFLD are represented by a lower BMI relative to the inhabitants of the low mountains. In women, the levels of SMM and the percentage of fat are significantly and statistically significantly correlated (r=-0.971; p<0.001), while in men these two indicators are not related. Men showed a trend towards higher percentages of fat, regardless of body weight and region of residence. For women, this indicator was within acceptable limits and did not exceed 31%. There was found a statistically significant difference in total cholesterol levels between low and middle mountain people in the group of obese patients (p<0.001) suffering from NAFLD. Statistically significant low ALT indices were revealed in the group of obese patients living in mid-mountain conditions.

Conclusion. Taken together, our results suggest that chronic mid-mountain hypoxia may slow down the course of overweight-induced NAFLD.