Relationship between Obesity and Iron Deficiency in Healthy Adolescents.

The relationship between overweight/obesity (excess of weight [EW]) and iron deficiency (ID) is not well defined. Objective: To analyze the relationship between EW and ID in healthy adolescents, assessing the contribution of new diagnostic measures of iron status and erythropoietic activity. Method: A cross-sectional study was made of 405 healthy adolescents, 12-16 years of age. A total of 289 were normal weight (NW) and 116 were otherwise healthy EW. Epidemiological, socioeconomic, diet, BMI Z-score, CRP (C-reactive protein), hematological, iron status, and erythropoietic activity parameters were measured. Statistical tests were Student's, analysis of variance (ANOVA), Chi-square, Pearson's correlation, and odds ratio. Results: ID prevalence in the EW group was 22.6% vs. 29.5% in the NW group (p: 0.3). Greater body weight was associated with lower reticulocyte hemoglobin content (CHr) (NW: 31.3 ± 1.7 pg vs. OW: 30.2 ± 1.7 pg, p: 0.007) and greater CRP (NW: 0.1 ± 0.2 mg/dL vs. OW: 0.2 ± 0.18 mg/dL, p < 0.001), leukocytes (NW: 6.69 ± 1.57 × 103/L vs. OW: 7.43 ± 1.63 × 103/L, p < 0.02), platelets (NW: 265.6 ± 58.9 × 103/L vs. OW: 291.8 ± 54.4 × 103/L, p < 0.002), ferritin (NW: 32.1 ± 17.9 ng/mL vs. OW: 42.8 ± 20.3 ng/mL, p: 0.01), serum transferrin receptor (sTfR) (NW: 1.39 ± 0.4 mg/L vs. OW: 1.73 ± 0.45 mg/L, p: 0.008), sTfR-F index (sTfR/log Ferritin) (NW: 1.06 ± 0.7 vs. OW: 1.33 ± 0.85, p: 0.036) and reticulocyte count (NW: 54.2 ± 18 × 103/L vs. OW: 65.4 ± 24.2 × 103/L, p: 0.003). A positive correlation was observed between the BMI Z-score and CRP, ferritin, sTfR, leukocytes, platelets, and reticulocyte count, and a negative one between the BMI Z-score and CHr and medium corpuscular volume. Conclusions: The prevalence of ID in otherwise healthy EW adolescents was no higher than in NW. The effect of obesity on iron status was low. The findings reveal the concomitant low-grade inflammation, and probably the effect of adiposity on erythropoietic activity. Specific cutoff values for ID in adolescents with OW need to be defined.