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 microg/l and mean corpuscular volume (MCV) <76 fl but 16% had depleted iron stores (SF<15 microg/l). Iron status indices were generally higher than at 1 and 2 y, but correlation was seen between iron status indices at 6 y and earlier values. Haemoglobin concentration at 6 y was negatively associated with length gain from birth to 1 y (B+/-s.e.=-1.269+/-0.452; P=0.007; adj. R2=0.119) (n=52), and proportional weight gain from birth to 1 y was higher among children with SF<15 microg/l at 6 y (295+/-33%; n=10) than those with SF> or =15 microg/l (258+/-31%; n=49) (P=0.001). MCV at 2 y predicted weight gain from 2 to 6 y (B+/-s.e.=1.721+/-0.581; P=0.005; adj. R2=0.153) (n=44); also, children with SF<15 microg/l at 6 y (n=9) gained 7.8+/-1.2 kg from 2 to 6 y, while children with SF> or =15 microg/l (n=35) gained 9.6+/-2.8 kg (P=0.007), furthermore a difference was seen in proportional weight gain from 2 to 6 y between children with depleted iron stores at 2 y and not, or 156+/-13 vs 169+/-18% (P=0.038).

CONCLUSION: The results suggest that low iron status at 1 and 2 y might lead to slower growth up to 6 y of age. Low iron status at 1 and 2 y and/or slower growth from 1 and 2 y up to 6 y might contribute to worse iron status at 6 y, while faster growth in early childhood is related to lower iron status.