Iron deficiency in children with a focus on inflammatory conditions.

Iron deficiency (ID) tends to be overlooked compared with anemia. However, its prevalence is estimated to be twice as high as that of ID anemia, and ID without anemia can be accompanied by clinical and functional impairments. The symptoms of ID are nonspecific, such as fatigue and lethargy, but can lead to neurodevelopmental disorders in children, restless legs syndrome, and recurrent infections due to immune system dysregulation. In particular, the risk of ID is high in the context of chronic inflammatory diseases (CIDs) due to the reaction of various cytokines and the resulting increase in hepcidin levels; ID further exacerbates these diseases and increases mortality. Therefore, the diagnosis of ID should not be overlooked through ID screening especially in high-risk groups. Ferritin and transferrin saturation levels are the primary laboratory parameters used to diagnose ID. However, as ferritin levels respond to inflammation, the diagnostic criteria differ among guidelines. Therefore, new tools and criteria for accurately diagnosing ID should be developed. Treatment can be initiated only with an accurate diagnosis. Oral iron is typically the first-line treatment for ID; however, the efficacy and safety of intravenous iron have recently been recognized. Symptoms improve quickly after treatment, and the prognosis of accompanying diseases can also be improved. This review highlights the need to improve global awareness of ID diagnosis and treatment, even in the absence of anemia, to improve the quality of life of affected children, especially those with CIDs.