Male gender is an important clinical risk factor for iron deficiency in healthy infants

Author's personal copy ; Acknowledgements to the children and families who were involved in this study, and to BH Pathology Clinic Dpt.Background & aims: To identify ID risk factors in infancy, and try to explore why ID is more prevalent in boys than in girls in the first year of life. Methods: A multiple logistic regression was performed on data of 201 infants, with ferritin<12 ng/ml as the dependent variable and months of breastfeeding, weight gain from birth to 9 months (WG), and gender as independent variables. To compare haematological parameters we used Manne-Whitney and t test. Results: From the 39 infants with IDA (19.4%), 24 (61.5%) were male and of the 162 infants without IDA, 50% were male (p ¼ 0.195). The median(minimum; maximum) ferritin concentrations in male infants at 9 months was of 9.8 ng/ml (0.5e67.0 ng/ml) and in females 14 ng/ml (0.5e74.5 ng/ml), p < 0.001. The average (±SD) WG was of 5863.3 g (±855.4 g) in male infants and 5556.9 g (±1054.3 g) in female infants (p = 0.027). A multiple logistic regression (OR; 95%CI) showed that male gender was the most important risk factor (OR: 3.3; 1.7e6.3; p < 0.001), followed by a higher weight increase (OR: 1.6; CI [1.1; 2.2]; p = 0.016) and longer breastfeeding time (OR: 1.1; CI [0.98; 1.2]; p = 0.099). Comparison of other haematological parameters at 9 months in relation to gender (males (M): 105; females (F): 96) showed significant differences in: mean ± SD, Mean Corpuscular Haemoglobin (M: 25.0 ± 2.1; F: 25.8 ± 2.4 pg, p = 0.001), Mean Corpuscular Volume (M: 73.4 ± 4.1; F: 75.3 ± 4.2 fl, 0.009), RDW (M: 14.6 ± 1.5; F: 14.1 ± 1.6%, p = 0.048), Plaquelets (M: 324.9 ± 77.9; F: 350.5 ± 81.4 x 10³/µl, p = 0.026). Conclusions: ID was significantly more frequent in male infants, independent of rapid growth or longer breastfeeding duration. The clinical risk profile for ID in infants includes male gender and not only rapid growth, and longer breastfeeding duration.This study received a scholarship from the Foment Commission for Investigation in Health Care, from the Health Ministry P.I. nº 87/07