SickKids finds an effective screening strategy for iron deficiency in young children

Research in children shows that iron is important for healthy brain development. Iron deficiency is a common problem, most frequently seen among children one to three years of age. Since early childhood is a sensitive time for brain development and maturation, iron deficiency in this age group may lead to serious effects on the brain and consequent developmental delays.

Dr. Patricia Parkin, Research Director, Paediatric Outcomes Research Team, Division of Paediatric Medicine at The Hospital for Sick Children (SickKids) and her team have studied iron deficiency in children for several years. The focus of their latest study, published in the November 28 online edition of Pediatrics, was to determine if a screening program can lead to early detection of iron deficiency.

In the United States, the American Academy of Pediatrics recommends screening all children at 12 months of age with a blood test for hemoglobin (there are no screening recommendation in Canada). “The problem with this approach,” says Parkin, “is that the blood test for hemoglobin detects anemia, and this is a late stage of iron deficiency. Some children with severe anemia require hospitalization and blood transfusions. Secondly, it is not known if 12 months is the best age to screen for iron deficiency.”

The team tested a screening program using a blood test for a protein called ferritin. The ferritin blood test was developed several decades ago and measures iron stores in the body but, until this study, had not been used as a screening test for early identification. The early stage of iron deficiency results in a low ferritin level; if iron deficiency continues to progress, ferritin may continue to fall and eventually the child may become anemic with a low hemoglobin.  

The study had more than 1,700 participants. Each child, ranging in age from one to three years, had a blood test for ferritin and hemoglobin. Overall, 12 per cent of children had a low ferritin level indicating iron deficiency. Compared with hemoglobin, ferritin was a more sensitive and specific test of iron deficiency. The age at which iron deficiency peaked was approximately 15 to 18 months.

“We found that using the ferritin blood test leads to early detection rather than late detection when the child already has anemia. We also discovered that between 15 and 18 months is the best age to screen for an iron deficiency,” says Parkin, who is also Professor, Department of Paediatrics, University of Toronto. “I am always interested in ways we can promote health and prevent disease, either by preventing it in the first place entirely, or through screening and early detection. It seems like iron deficiency in early childhood is a condition well-suited for prevention.”

In Ontario, children are regularly scheduled to see their primary care physician at 15 and 18 months of age for a health supervision visit. Parkin says this could be an ideal time to discuss whether screening for iron deficiency would be an appropriate choice. The blood sample for ferritin is a commonly ordered test, available in most labs, and only requires a small amount of blood. If the child’s ferritin is low, parents can discuss strategies with their child’s physician to increase iron in the diet and whether oral iron supplements may be needed.

The next steps for Parkin’s research will include analyzing data obtained from long-term follow-up of this study to determine if early detection of iron deficiency, followed by diet counselling and/or oral iron supplements, leads to improvements in children’s development and cognition.

This study was conducted within the primary care research network called The Applied Research Group for Kids (TARGet Kids!). A partnership between primary care physicians in the community and child health researchers at SickKids, St. Michael’s Hospital and McMaster University, TARGet Kids! is the only research network embedded in primary care physician offices in community settings in Canada. When young children come for their regularly scheduled visits with their paediatrician or family physician, they are invited to participate. The network recently enrolled their 10,000th child. While collecting data and blood samples on young children is challenging (creating significant gaps in data in this age group), the approach by Parkin’s team overcame this by enrolling children who are attending regularly scheduled visits.

This work was supported by a grant from the Canadian Institutes of Health Research. Funding to support TARGet Kids! was provided by multiple sources including the Canadian Institutes for Health Research (CIHR), the SickKids Foundation and the St. Michael's Hospital Foundation.