584 Response to Intravenous Ferric Carboxymaltose in the Treatment of Childhood Restless Legs Syndrome/Periodic Limb Movement Disorder

Introduction Pediatric Restless Legs Syndrome (RLS)/Periodic Limb Movement Disorder (PLMD) are treatable disorders affecting quality of life. The first line therapy is oral iron, which may have gastrointestinal side effects or suboptimal absorption. Consequently, parenteral iron preparations are needed, but have been insufficiently studied in children. This study evaluates the response to intravenous ferric carboxymaltose (FCM) in pediatric RLS/PLMD. Methods We performed a retrospective chart review of children who received FCM between May 2018 and January 2019 for treating RLS/PLMD. Serum ferritin before and after the infusion were compared. Where possible, the Clinical Global Impressions of Improvement (CGI-I) was evaluated. Side effects documented in the charts were extracted. The median administered dose of FCM was 10.1 mg/kg (range 9.6–20.8) over 0.6 to2 hours. Results There were 27 patients, with mean age of 10.0 +/-4.2 years. 52% were female. 24 had RLS and 3 had PLMD. 20/27 (69.7%) had prior oral iron therapy; 4/20 (26.0%) experienced side effects. Adverse events from FCM infusion included procedure-related anxiety in 4/27, nausea in 1/27, infusion site pain in 2/27, and tachycardia in 1/27. One patient developed subcutaneous extravasation of iron with brownish skin discoloration and a resulting adjustment disorder. Three patients had phosphorus checked following infusion; all were normal. Serum ferritin was available both before and after the infusion for 17 patients. Mean serum ferritin prior to infusion was 27.2 +/-15.7 µg/L (range 6–58) and after the infusion it was 109.8 +/-49.34 µg/L (range 27–192). Mean ferritin increase was 82.6 +/-41.5 µg/L (range 14–160; p=0.0001). Post-infusion ferritin was over 50 µg/L for all but 2 of the subjects, with follow up ranging from 31–266 days (mean 120 days). A larger increase was seen at higher doses (p=0.01). Ferritin increase was not impacted by age, gender, symptom severity, PLMI or prior ferritin level. CGI-I was applied to 15 patients with sufficient follow-up documentation and showed improvement in 86%, with 79% much or very much improved. Conclusion The administration of FCM in children with RLS/PLMD is associated with a satisfactory rise in serum ferritin and modest symptomatic improvement. Support (if any):