Iron deficiency in infancy: applying a physiologic framework for prediction.
BACKGROUND
Infants aged 6-24 mo are at high risk of iron deficiency. Numerous studies worldwide have sought to identify predictors of iron deficiency in this age group.


OBJECTIVE
The objectives of the study were to apply a physiologic model to identify risk factors for iron deficiency and to consider those risk factors under different conditions of iron supplementation. We predicted that factors related to iron status at birth (lower gestational age and lower birth weight), postnatal needs for iron (more rapid growth), and bioavailable iron (more cow milk) would be major risk factors.


METHODS
The physiologic framework was assessed in 1657 Chilean infants (aged 12 mo) with birth weights >or=3 kg who were randomly assigned at age 6 mo to high or low iron supplementation or no added iron. Based on venous blood, the analysis used mean corpuscular volume and concentrations of hemoglobin, free erythrocyte protoporphyrin, and ferritin. Logistic regression models were used to identify predictors of iron deficiency anemia and iron deficiency without anemia.


RESULTS
The prevalence of iron deficiency (>or=2 abnormal iron measures) was 34.9% at age 12 mo. Of 186 infants with hemoglobin concentrations <110 g/L, 158 (84.9%) were iron deficient. The only consistent (and the strongest) predictor of iron deficiency or iron deficiency anemia was lower 6-mo hemoglobin. Factors related to poorer iron status at birth (lower birth weight, shorter gestation though full-term, or both) were predictors in the no-added-iron and high-iron groups. Otherwise, predictors varied by iron supplementation.


CONCLUSIONS
Variations in predictors of iron deficiency or iron deficiency anemia according to iron supplementation suggest that direct comparisons across studies are tenuous at best without data on early iron status and certainty that specific conditions are comparable.
Lozoff
Betsy
B
Center for Human Growth and Development, University of Michigan, Ann Arbor, MI 48109-0406, USA. blozoff@umich.edu
Kaciroti
Niko
N
Walter
Tomás
T
D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology*; D001682:Biological Availability; D001724:Birth Weight / Q000502:physiology; D002677:Chile / Q000453:epidemiology; D019587:Dietary Supplements; D004909:Erythrocyte Indices; D005260:Female; D005293:Ferritins / Q000097:blood; D005865:Gestational Age; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007223:Infant; D007228:Infant Nutrition Disorders / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology*; D007227:Infant Nutritional Physiological Phenomena; D007501:Iron / Q000097:blood; D000090463:Iron Deficiencies; D019266:Iron, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016015:Logistic Models; D008297:Male; D009751:Nutritional Requirements; D009752:Nutritional Status; D011237:Predictive Value of Tests; D012307:Risk Factors; D014131:Trace Elements / Q000097:blood / Q000172:deficiency
D006454:Hemoglobins; D019266:Iron, Dietary; D014131:Trace Elements; D005293:Ferritins; D007501:Iron