Comparison between oral ferrous sulfate and intravenous ferric carboxymaltose in children with restless sleep disorder

Study Objectives: Recent work has identified clinical and polysomnographic features of a newly defined pediatric sleep disorder, restless sleep disorder (RSD). One of these features is low serum ferritin. In this retrospective, pilot study, we assess the response to iron supplementation. Children were given oral ferrous sulfate (FS) or intravenous ferric carboxymaltose (IV FCM). Methods: Children 5-18 years old with a diagnosis of RSD were evaluated clinically. Serum ferritin, iron profile, and video-polysomnography were obtained at baseline. Oral or IV iron supplementation was offered as part of routine care. Oral FS was one 325 mg tablet daily or 3 mg/kg/day liquid for 3 months. IV FCM was 15 mg/kg, up to 750 mg as a single infusion. Adverse effects were assessed. Ferritin and iron profile were checked after 2-3 months. Eight weeks after FCM, the phosphorus level was checked. Clinical Global Impression (CGI) scale was obtained pre- and posttreatment. Results: A total of 15 children received oral FS and 15 IV FCM. Baseline RSD severity, age, gender, or pretreatment lab values did not differ significantly between groups. CGI-improvement median score was "minimally improved"after oral FS and "much improved"after IV FCM (effect size 1.008, p < 0.023). All iron parameters were found to be significantly higher after intravenous iron treatment than oral iron, especially ferritin (effect size 3.743, p < 0.00003). Adverse effects: constipation, three with FS; noncompliance, one with FS; syncope, one with FCM infusion; and hypophosphatemia, zero post-FCM. Conclusions: In this retrospective, clinical case series, RSD responded to iron supplementation with improvement in both clinical and laboratory parameters. The response was greater with IV FCM than oral FS.