Serum irisin levels in metabolically healthy versus metabolically unhealthy obesity: A case-control study

Metabolically healthy obese (MHO) individuals appear to be protected or more resistant to the progression of obesity-related metabolic disorders. Hormonal regulation associated with adipose or muscular tissues such as irisin and leptin may facilitate the healthy metabolic profile of MHO cases. In this case-control study, the differences between serum level of irisin was investigated in metabolically unhealthy obese (MUO) and metabolically healthy obese (MHO) individuals.

The study participants included obese individuals with metabolic syndrome (MetS) (n=51) and 2 control groups that included weight matched cases without MetS (n=51) and normal weight cases without MetS (n=51). Diagnosis of MetS was made based on the Adult Treatment Panel III (ATPIII) criteria. Serum levels of leptin and irisin were determined by enzyme-linked immune-sorbent assay (ELISA) kit. Receiver Operator Characteristic (ROC) curve, multiple linear regression, and one-way ANOVA analysis were used in SPSS 16 software. Significant level was set at 0.05.

Based on the statistical analysis, serum levels of irisin were 2.91±1.6, 3.14±1.4, and 4.47±3.23 (ng/mL) in MUO, MHO, and nonobese metabolically healthy participants, respectively (P = 0.001). Also, serum levels of leptin were 14.06±12.4, 11.2±9.3, and 7.09±7.1 (ng/mL) in MUO, MHO, and nonobese metabolically healthy cases, respectively (p=0.002). After adjusting for demographic variables, a significant association was found between irisin and study groups (β = 0.77, P = 0.001), weight (β=-0.03, p=0.014), BMI (β=-0.11, p=0.006), TG (β=-0.003, p=0.025), fat mass (β=-0.04, p=0.046), and fat free mass (β=0.08, p=0.014).

Obese patients with/without MetS had lower level of irisin than normal weight participants.