Ferric carboxymaltose effects on restless legs syndrome and on brain iron in patients with iron deficiency anemia

Brain iron status is fundamental in RLS pathogenesis. The aim of this study was to determine the clinical efficacy and brain iron concentration improvement in RLS patients with IDA, using 1500 mg FCM. This is a randomized, double-blinded, placebo-controlled study. RLS patients with IDA were grouped into either 1500 mg FCM or placebo. The primary outcomes were the change from baseline on the International Restless Legs Syndrome Study Group scale (IRLS) and brain iron measured by QSM and R2∗. A total of 18 RLS patients with IDA were enrolled, 10 in the FCM group and 8 in the placebo. At the week 6 endpoint, the FCM group showed significant improvement in both IRLS (−13.60 ± 9.47 vs. −3.63 ± 5.40, p = 0.011) and VAS (−40.50 ± 28.81 vs. −0.63 ± 28.28, p = 0.004) from baseline. Change from baseline with R2∗ techniques showed a treatment effect for the thalamus and QSM technique for both the substantia nigra and pulvinar. A correlation was proved between the IRLS difference and the difference of QSM in thalamus (p = 0.028). This study demonstrates that 1500 mg FCM effectively treats RLS symptoms in IDA patients over six weeks, with MRI measurements of improved brain iron content serving as a potential biomarker for RLS patients.