Efficacy of oral iron in patients with restless legs syndrome and a low-normal ferritin: A randomized, double-blind, placebo-controlled study

Abstract 

Background and Purpose

Restless Legs Syndrome (RLS) is a primary disorder of sensation that affects sleep and has been associated with iron deficiency. The purpose of this study was to determine if symptomatic RLS patients with low-normal serum ferritin levels benefit from oral iron replacement.

Patients and Methods

This was a randomized, placebo-controlled, double-blinded study. Eligible patients were randomized to oral iron therapy vs. appearance-matched placebo and followed over a 12 week period.

Results

Baseline International Restless Leg Scale (IRLS) scores for the treatment (24.8±5.72) and placebo (23.0±5.03) groups were similar. Baseline ferritin levels for the treatment (40.6±15.3ng/ml) and placebo (36.7±20.8ng/ml) groups were also similar. After 12 weeks, IRLS scores decreased more in the treatment arm (10.3±7.40) than in the placebo arm (1.14±5.64), (p=0.01). Ferritin levels increased more in the treatment arm (25.1±20.3ng/ml) than in the placebo arm (7.5±13.7ng/ml), (p=0.04). We observed a nonsignificant trend toward improved quality of life in the treated patients, (p=0.07).

Conclusions

This is the first double-blinded, placebo-controlled study to demonstrate statistically significant improvement in RLS symptoms using oral iron therapy in patients with low-normal ferritin. The findings from this study suggest that additional larger randomized placebo-controlled trials of iron as treatment for patients with low-normal ferritin are warranted.

Keywords: Restless legs syndrome, Iron sulfate, Iron deficiency, International Restless Legs Scale (IRLS), Clinical trial, Ferritin