Repeated IV doses of iron provides effective supplemental treatment of restless legs syndrome

Abstract

Background and purpose To evaluate in RLS patients the efficacy and safety of repeated infusions of iron in order to maintain symptomatic improvements achieved with a prior single 1000 mg infusion of iron. Patients and methods Subjects who had demonstrated initial improvement in RLS symptoms after a single 1000 mg infusion of iron were evaluated monthly for serum ferritin and RLS severity. If symptoms returned at any time in the 2-year period after initial iron treatment, supplemental 450 mg iron gluconate infusions could be given, provided the ferritin was <300 mcg/l. The primary outcome measures were side effect profile, duration (weeks) of sustained improvement, and rate of change of serum ferritin. Results Ten subjects received the initial single 1000 mg dose of iron dextran, but only five subjects were eligible to receive supplemental iron infusions. RLS symptoms returned on average 6 months after the initial 1000 mg infusion. Because of noncompliance with monthly visits one subject was dropped after receiving three supplemental iron infusions. Because of a ferritin >300 mcg/l, a second subject was dropped after having received one supplemental treatment. Three subjects completed the 2-year period of the study, having received between two and four courses of supplemental iron. After the initial 1000 mg iron infusion, the ferritin declined on average 6.6 mcg/l/week, which was substantially higher than the predicted value of <1 mcg/l per week. The rate of ferritin decline decreased toward normal with repeated IV iron treatments: the average rate of decline in ferritin for the last treatment course was 2.3 mcg/l/wk. The slower the rate of ferritin decline the more prolonged the symptom improvements. Conclusions Supplemental iron treatments can sustain previously achieved improvements with a single IV iron treatment, but achieving high ferritin levels was not in themselves a guarantee of sustained improvements. The most notable finding was the post-infusion changes in serum ferritin and its implication for altered iron excretion.