Serum ferritin and hematological indices in children with attention-deficit/hyperactivity disorder: a matched...

ADHD is a common neurodevelopmental disorder with substantial clinical heterogeneity. Iron is essential for brain development and dopaminergic function, and altered iron homeostasis may contribute to ADHD pathophysiology. However, evidence on peripheral iron biomarkers remains inconsistent. To compare iron-related biomarkers and hematological indices between children with ADHD and neurotypical controls and to assess whether serum ferritin is independently associated with ADHD.

This age- and sex-frequency-matched case-control study included 50 children with ADHD recruited from the pediatric neurology and child psychiatry outpatient clinics and 50 neurotypical controls recruited from the general pediatric outpatient clinic of the same tertiary hospital between March 2023 and March 2024. Serum ferritin, serum iron, total iron-binding capacity (TIBC), hemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were measured using standardized laboratory methods. Group comparisons were performed using independent-samples t tests and chi-square tests. Multivariable logistic regression was used to examine the independent association between ferritin and ADHD after adjustment for relevant covariates.

Children with ADHD had significantly lower serum ferritin levels than controls (38.4 ± 17.4 vs. 51.2 ± 19.8 ng/mL; p < 0.001). Serum iron was also lower in the ADHD group (83.3 ± 25.0 vs. 97.6 ± 22.4 µg/dL; p = 0.004), whereas TIBC was higher (356 ± 48 vs. 334 ± 42 µg/dL; p = 0.019). Iron deficiency (ferritin < 30 ng/mL) was more common in children with ADHD (34.0% vs. 14.0%; p = 0.018). Hemoglobin, MCV, MCH, and MCHC did not differ significantly between groups. In multivariable analysis, lower ferritin remained independently associated with ADHD (adjusted OR = 1.42 per 10 ng/mL decrease; 95% CI: 1.08-1.86; p = 0.011).

Children with ADHD had lower iron stores despite largely normal routine hematological indices. These findings support a potential role for altered iron metabolism in ADHD and suggest that ferritin assessment may provide clinically useful information beyond routine blood counts.