title: Investigating the response to intravenous iron in restless legs syndrome: an observational study.
abstract: 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.
authors.affiliation: Interdisciplinary Pain Centre, University Medical Centre, Freiburg, Germany. magdolna.hornyak@uni-ulm.de
authors.forename: Magdolna
authors.initials: M
authors.lastname: Hornyak
authors.forename: Hanna
authors.initials: H
authors.lastname: Scholz
authors.forename: Andrea
authors.initials: A
authors.lastname: Kiemen
authors.forename: Jan
authors.initials: J
authors.lastname: Kassubek
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D005260:Female; D005290:Ferric Compounds / Q000008:administration & dosage* / Q000097:blood; D005293:Ferritins / Q000097:blood / Q000172:deficiency; D006801:Humans; D007275:Injections, Intravenous; D007501:Iron / Q000097:blood*; D000090463:Iron Deficiencies; D008297:Male; D008320:Maltose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D008875:Middle Aged; D011446:Prospective Studies; D012148:Restless Legs Syndrome / Q000097:blood* / Q000188:drug therapy* / Q000453:epidemiology; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D005290:Ferric Compounds; C522335:ferric carboxymaltose; D008320:Maltose; D005293:Ferritins; D007501:Iron