Higher Body Mass Index Is Associated with Iron Deficiency in Children 1 to 3 Years of Age

OBJECTIVES: To examine the association between body mass index (BMI) and iron deficiency in early childhood, while considering the influence of low-grade systemic inflammation. STUDY DESIGN: Healthy children ages 1-3 years were included in a cross-sectional analysis. Age- and sex-standardized World Health Organization BMI z score (zBMI) was calculated using height/length and weight measurements; iron status was assessed by serum ferritin; inflammation was assessed by C-reactive protein (CRP). Children with CRP ≥10 mg/L were excluded because this may indicate acute systemic inflammation. Adjusted multivariable regression analyses were used to investigate the association between zBMI and both serum ferritin (µg/L), and iron deficiency (serum ferritin <12 µg/L). We performed prespecified subgroup analyses according to CRP level (normal [≤1.0 mg/L] and low-grade inflammation [>1.0 mg/L to <10.0 mg/L]). RESULTS: Of 1607 children included, 20% were categorized as with zBMI >1, 13% had iron deficiency, and 18% had low-grade inflammation. Higher zBMI was associated with lower serum ferritin (-1.51 µg/L, 95% CI -2.23, -0.76, P < .0001) and increased odds of iron deficiency (OR 1.28, 95% CI 1.10, 1.50, P = .002). Though there was no interaction between zBMI and CRP for the adjusted linear regression model (P = .79) or logistic regression model (P = .43), children with low-grade inflammation had a higher serum ferritin (P < .0001). CONCLUSIONS: Higher zBMI is associated with increased risk for iron deficiency in children between 1 and 3 years, and should be considered as a risk factor in targeted screening. Further research is needed to better understand the relationship between serum ferritin and CRP for children in all weight categories. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01869530.