Reduced brain iron is strongly associated with restless legs syndrome (RLS). Oral iron supplements are commonly recommended for RLS but are largely ineffective due to poor absorption and poor tolerability at required doses. Intravenous iron dextran has been shown to increase brain iron content. Surprisingly only a few reports have ever presented data on the clinical effect of high dose intravenous iron for RLS. We retrospectively identified 25 subjects (age 53.2+/-11.9, 7 male) that received intravenous iron for RLS refractory to conventional treatments. We infused 1g of high molecular weight iron dextran over five hours. The age of RLS onset was 32.6+/-13.0 years and 15 subjects had a positive family history of RLS. Patients attempted 7.5+/-2.7 medications for RLS prior to iron therapy. Baseline ferritins ranged from 5 to 248 ng/ml (mean 43.5+/-58.0) and 20/25 had ferritins of less than 50. Two subjects did not complete their entire infusion due to anaphylactic type symptoms but are included. Overall, 2 subjects reported complete amelioration of all RLS symptoms, 11 reported marked improvement, 2 moderate improvement, 3 mild improvement, and 6 reported no improvement. For those with improvement, the duration of effect was highly variable (mean 15.8+/-17.7 weeks, range 1-60 weeks). Twelve subjects had multiple infusions. Iron dextran can dramatically improve refractory RLS but results are inconsistent and not predicted by patient demographics. Although burdened by a higher rate of anaphylactic reactions, iron dextran may be superior to other IV iron preparations.
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