Treatment of Childhood-onset Restless Legs Syndrome and Periodic Limb Movement Disorder Using Intravenous Iron Sucrose

Objective: An alternative treatment approach is needed for children who cannot tolerate oral iron preparations or when there is a need for rapid replenishment of iron stores. We report on the safety, adverse effects, and efficacy of intravenous iron sucrose in a retrospective sample of children with restless legs syndrome (RLS) or periodic limb movement disorder (PLMD).

Methods: Sixteen children with RLS/PLMD who received intravenous iron sucrose at our institution between 2005 and 2011 were identified. The diagnosis of RLS/PLMD was established after formal sleep consultation and nocturnal polysomnography (PSG). Serum ferritin was assayed in all 16 subjects prior to iron sucrose infusion and in 14 subjects after infusion. The medical records were reviewed for treatment-related details.

Results: The mean age of subjects was 6.6 years (range, 2-16 y; 5/16 girls). The mean periodic limb movement index (PLMI) was 18.2±12.8. Fifteen of the 16 subjects (93.7%) had systemic or neurologic comorbidities. Fourteen of 16 (87.5%) subjects had received prior oral iron supplementation for sleep-related concerns, with the majority of the subjects either having gastrointestinal (GI) side effects or insufficient benefits. Intravenous iron sucrose therefore was provided to these 16 subjects through our outpatient pediatric infusion therapy center. The average dose of intravenous iron sucrose of 3.6 mg/kg was infused over 2 h. The baseline mean serum ferritin was 16.4±6.6 ng/mL. After infusion with intravenous iron sucrose, the mean serum ferritin rose to 45.7±22.4 ng/mL (n=14; [95% confidence interval, 17.2-41.3]; P<.0001). Parental assessment of response to iron sucrose therapy was conducted on follow-up clinic visits or via telephone calls. There was improved sleep in 62.5% (n=10) of subjects and no improvement in 12.5% (n=2) of subjects. No follow-up information was available for 25% (n=4) of subjects. Minor adverse events occurred in 25% (n=4) of subjects--two subjects experienced difficulty with peripheral intravenous catheter placement, while two had transient GI symptoms, such as anorexia, nausea, and vomiting. None of the subjects had anaphylaxis.

Conclusions: Intravenous iron sucrose appears to be a relatively effective therapy for patients with childhood-onset RLS/PLMD and iron deficiency who do not tolerate or respond to oral iron supplements. Side effects were transient. The most common adverse events were difficulty with intravenous line placement and GI disturbance. There is a need for systematic prospective studies on the safety and efficacy of intravenous iron sucrose in RLS/PLMD in children.