Are Doctors Missing Iron Deficiency in Children?

Iron deficiency is the most common nutritional deficiency worldwide, and new research published in Blood Red Cells & Iron, a journal of the American Society of Hematology, suggests that many children may be iron-deficient long before they develop anemia. Investigators are now questioning whether current screening guidelines in the United States are missing a large number of children who could benefit from earlier detection and treatment.

Iron is essential for energy, growth, brain development, concentration, immune function and oxygen transport throughout the body.

“Identifying the ferritin level in blood needed to support a child’s physical growth and learning is important because low iron levels can lead to serious health issues such as difficulties with concentration and learning, fatigue and reduced physical performance,” said lead investigator Yaw Addo, Ph.D., an epidemiologist in the Division of Nutrition, Physical Activity and Obesity at the Centers for Disease Control and Prevention (CDC).

Currently, the CDC defines iron deficiency in children using a blood marker called ferritin, with levels of 15 micrograms per liter or lower considered deficient. Ferritin reflects the body’s stored iron. However, in this new study, a team of investigators analyzed iron and blood data from more than 3,700 healthy U.S. children between the ages of 5 and 14 and found evidence that the body may begin showing signs of iron deficiency at much higher ferritin levels — closer to 24-25 micrograms per liter.

To better understand when iron deficiency truly begins, investigators looked at ferritin alongside hemoglobin levels and another marker called zinc protoporphyrin (ZPP), which can signal when the body is struggling to make healthy red blood cells. They found that the “tipping point” where iron-related changes began occurring was consistent across ages and sexes and significantly higher than current CDC cutoffs.

The findings could have major implications for children’s health. Using the current CDC definition, about 9% of children in the study were classified as iron-deficient. But when researchers used the higher, physiologically based ferritin thresholds, the estimated rate jumped to 30%.

Importantly, rates of iron-deficiency anemia remained very low regardless of which threshold was used. That suggests many children may experience iron deficiency before developing anemia — meaning a child could still have normal hemoglobin levels while their body is already lacking enough iron.

The team says this study had several important strengths, including its large sample size and focus on apparently healthy children between the ages of 5 and 14. By using robust statistical methods and multiple iron-related biomarkers, the investigators were able to identify consistent ferritin thresholds that may better reflect when iron deficiency truly begins in children.

The study also included additional analyses to account for possible effects of lead exposure, which can interfere with iron measurements, and the team found the results remained consistent. Another strength was that the findings aligned with more recent national survey data and additional iron biomarkers, helping validate the proposed higher ferritin thresholds.

At the same time, they noted several limitations. Some newer and potentially more sensitive iron biomarkers were not available in the older national database used for this research. The study also could not fully account for puberty-related changes, such as menstruation or maturation stage, which can affect iron levels, because that information was incomplete for younger children in the data set. Investigators also acknowledged that more research is still needed to understand how these findings relate to real-world outcomes like learning, cognition and child development.

The study highlights the need to rethink how iron deficiency is identified in children and suggests doctors may need to consider higher ferritin levels when evaluating symptoms or screening for iron deficiency. The findings also reinforce that anemia alone may not be enough to identify early iron problems in growing children.