Relationship between Serum Levels of Body Iron Parameters and Insulin Resistance and Metabolic Syndrome in Korean Children

OBJECTIVES: An increase in serum ferritin and levels of the cleaved soluble form of transferrin receptor (sTfR) are related to several metabolic conditions. We evaluated the relationship between body iron status indicators, including ferritin and sTfR, and insulin resistance and metabolic syndrome (MetS) in Korean children. METHODS: A cross-sectional study was conducted on 1350 children in Korea. Anthropometrical parameters; lipid profiles; levels of glucose, insulin, and leptin; and iron status indicators, including sTfR, serum ferritin, serum iron, total iron-binding capacity (TIBC), and transferrin saturation (TS), were analyzed. RESULTS: Although serum sTfR levels were significantly higher in boys than in girls (2.20 vs. 2.06 mg/L, p < 0.0001), serum iron and TS were higher in girls than in boys (101.38 vs. 95.77 mg/L, p = 0.027 and 30.15 vs. 28.91%, p = 0.04, respectively). Waist circumference (WC) and leptin were most significantly associated with body iron indicators when adjusted for age and sex. After adjusting for age, sex, and WC, sTfR levels showed the strongest positive association with leptin levels (p = 0.0001). Children in the highest tertile for homeostasis model assessment-insulin resistance (HOMA-IR) had higher TIBC (p = 0.0005) and lower serum iron (p = 0.0341), and the lowest TS (p < 0.0001) after adjustment for confounders. Children with higher sTfR were most significantly associated with risk of MetS compared with those lower sTfR (p = 0.0077). CONCLUSION: The associations of serum levels of iron metabolism markers with leptin levels, HOMA-IR, and MetS suggest that iron-related factors may involve insulin resistance and MetS.