Determinants of ferritin response to oral iron supplementation in children with sleep movement disorders

STUDY OBJECTIVES: To identify children who respond to oral iron supplementation as evidenced by increased ferritin levels and to identify factors that correlate with improvement in ferritin levels in those who respond.

METHODS: A retrospective chart review of the PLMS/RLS/RSD database at Seattle Children's Hospital was carried out. Data collected included nocturnal polysomnography parameters, age, sex, initial and follow-up ferritin level and date of collection, and presence of RLS, PLMS/PLMD, RSD, obstructive sleep apnea (OSA), neurologic, psychiatric, neurodevelopmental, or medical comorbidity. Oral iron therapy was evaluated by side effects (none; constipation; bad taste/nausea), subjective outcome in symptoms (resolved, improved, no change), and adherence to therapy (poor, fair, good).

RESULTS: Seventy-seven children were included in this study of whom 42 were classified as responders (increase in ferritin of ≥10 µg/L) and 35 were non-responders. Age and sex were not different between groups. Adherence was the only significant predictor of an increase in ferritin of ≥10 µg/L. Constipation was seen in 7.1% of responders vs. 45.8% of non-responders. No change in symptoms was reported in 26.2% of responders vs. 71.4% in non-responders. A significant correlation was found between treatment duration and ferritin level change in responders but not in non-responders.

CONCLUSIONS: Side effects hinders adherence to oral iron supplementation in children. Responders to oral iron show improvement in ferritin levels and symptoms, while non-responders show no improvement in ferritin levels despite a long-lasting treatment, at least in part of them.