Iron status in 6-y-old children: associations with growth and earlier iron status

Objective: To investigate the iron status of 6-y-old children and its association with growth and earlier iron status. Design: In a cross-sectional study, children's body size measurements were recorded and blood samples taken near their sixth birthday. Subjects: A sample of 188 children, randomly selected in two previous studies, was contacted, and 139 (74%) agreed to participate. Results: No children had iron deficiency anaemia, one was iron-deficient (serum ferritin (SF)< 15 mu g/l and mean corpuscular volume (MCV)< 76) fl but 16% had depleted iron stores (SF < 15 mu g/l). Iron status indices were generally higher than at 1 and 2y, but correlation was seen between iron status indices at 6y and earlier values. Haemoglobin concentration at 6y was negatively associated with length gain from birth to 1y (B +/- s.e.=-1.269 +/- 0.452; P=0.007; adj. R-2=0.119) (n=52), and proportional weight gain from birth to 1y was higher among children with SF < 15 mu g/l at 6y (295 +/- 33%; n=10) than those with SF >= 15 mu g/l (258 +/- 31%; n=49) (P=0.001). MCV at 2y predicted weight gain from 2 to 6y ( B +/- s.e.=1.721 +/- 0.581; P=0.005; adj. R-2=0.153) (n=44); also, children with SF < 15 mu g/l at 6y (n=9) gained 7.8 +/- 1.2kg from 2 to 6y, while children with SF >= 15 mu g/l (n=35) gained 9.6 +/- 2.8kg (P=0.007), furthermore a difference was seen in proportional weight gain from 2 to 6y between children with depleted iron stores at 2y and not, or 156 +/- 13 vs 169 +/- 18% (P=0.038). Conclusions: The results suggest that low iron status at 1 and 2y might lead to slower growth up to 6y of age. Low iron status at 1 and 2y and/or slower growth from 1 and 2y up to 6y might contribute to worse iron status at 6y, while faster growth in early childhood is related to lower iron status. Sponsorship: The Icelandic Research Council.