Association of fibroblast growth factor 21 with metabolic phenotype and fat depots in young adults with abdominal obesity

Fibroblast Growth Factor 21 (FGF21) is a hormone-like protein involved in the regulation of energy balance and glucose and lipid homeostasis. The study of the association of this factor with the metabolic phenotype – metabolically healthy (MHAO) and metabolically unhealthy abdominal obesity (AO) and different fat depots (visceral, subcutaneous, epicardial, perivascular) in young people is of undoubted scientific and practical interest. Aim. To determine serum FGF21 levels and match it with the distribution of adipose tissue in young people with AO. Outcomes and methods. The study enrolled 132 people (mean age 37.59±6.35 years). 3 groups were formed: 0th – 16 conditionally healthy volunteers; 1st –46 people of 40 years [34; 43] with MHAO; 2nd – 70 people of 40 years [35; 44] with metabolic syndrome (MS). All subjects underwent measurement of height, body weight, waist circumference, calculation of body mass index. The FGF21 levels (ELISA KIT, BCM Diagnostics, Germany), lipid profile, 2-hour glucose tolerance test, glucose, insulin, leptin, adiponectin levels and HOMA-IR were assessed. Daily monitoring of blood pressure was performed. The volumes of subcutaneous, visceral, perivascular, epicardial fat, as well as subcutaneous fat to visceral fat ratio were determined with computed tomography. Additionally, for subanalysis, all patients (132 people, mean age 37.59±6.35 years) were divided into 6 groups depending on the presence of AO and the number of risk factors (RF): AO-0/FR-0 (n=16); AO-1/FR-0 (n=3); AO-1/FR-1 (n=40); AO-1/FR-2 (n=37); AO-1/FR-3 (n=14); AO-1/FR-4 (n=5). In each group, FGF21 levels was assessed. Results. The FGF21 levels was significantly higher in the groups of persons with MHAO (294.4 pg/ml) and MS (245.7 pg/ml) compared with the control group (110.2 pg/ml); p=0.04 and p=0.05, respectively. According to the correlation analysis data, there was significant weak association of FGF21 with age (r=0.22, p≤0.05), waist circumference (r=0.18, p≤0.05), hip circumference (r=0.26, p≤0.05), body mass index (r=0.3, p≤0.01). FGF21 was found to be associated with vis-ceral (r=0.2, p≤0.05) and subcutaneous (r=0.2, p≤0.05) fat depots. A significant association of FGF21 with triglycerides (r=0.21, p≤0.05) and leptin (r=0.24, p≤0.05) was registered. The FGF21 level ≥345.8 pg/ml reflected a 3-fold increase in the risk of MS in young people (AuROC 0.74, sensitivity 78.6%, specificity 75.0%, p<0.0001). The FGF21 levels ≥294.4 pg/ml was a risk marker for MHAO (AuROC 0,70, sensitivity 67.4%, specificity 75.0%, p<0.0001). According to the results of subanalysis, a significant (p<0.01) increase in the FGF21 concentration was revealed in the groups with an increase in the number of MS components. Conclusions. The FGF21 levels increases with the worsening of the metabolic phenotype; its increase is seen long before the formation of MS (in persons with MHAO). FGF21 in young people is associated with visceral and subcutaneous fat depots, triglyceride levels and leptin. FGF21≥345.8 pg/ml can be considered a predictor of MS in young people, but further research is required.