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Investigating the response to intravenous iron in restless legs syndrome: an observational study
Magdolna Hornyak1, Hanna Scholz, Andrea Kiemen
1Interdisciplinary Pain Centre, University Medical Centre, Freiburg, Germany. magdolna.hornyak@uni-ulm.de
Objective:
To investigate the effect of intravenous (IV) iron (500 mg ferric carboxymaltose [FCM] as a single dose) on restless legs syndrome (RLS) severity on a day-to-day basis.
Methods:
Twenty patients with RLS and absolute or functional iron deficiency or low normal serum ferritin (<45 μg/l) were included. Change of RLS severity was evaluated using the International RLS severity scale (IRLS) and the RLS-severity diary (RLS-SD) which evaluates symptom severity over a 6-h period on an 11-point numerical Likert scale, four times a day.
Results:
Twelve patients reported that IV FCM improved RLS ("responders"). IRLS score decreased from 30.1 (± 5.9) to 23.07 (± 9.5) (p=0.001) in the whole group and from 28.3 (± 6.1) to 18.3 (± 8.0) (p=0.002) in the responder group three weeks after IV FCM treatment. A clinically relevant effect of IV iron on RLS severity could be seen as early as day eight. The responder group differed from the non-responder group in tendency by being younger (p=0.064), having a lower serum ferritin level at baseline (p=0.097), and presenting a lower number of comorbid conditions.
Conclusions:
FCM led to a considerable improvement in RLS in the responder group within about one week. These findings are clinically relevant, especially for patients with severe RLS symptoms and iron deficiency, since a change or uptitration of RLS-specific medication can be avoided or postponed in these patients due to the rapid response to IV FCM treatment.
