The severity range of restless legs syndrome (RLS) and augmentation in a prospective patient cohort: association with ferritin levels.
OBJECTIVE
The aim of the study was to prospectively examine all patients with a diagnosis of RLS consulting a sleep disorders clinic and to assess RLS severity and augmentation and their associations, including ferritin levels.


METHODS
Patients were stratified into patients with RLS as ancillary diagnosis, RLS sufferers without current augmentation and RLS sufferers with current augmentation. Work-up included RLS severity scales and blood biochemical variables including indices of iron metabolism.


RESULTS
In an 18-month period, 302 patients with RLS (183 women, 119 men; mean age, 59.1+/-13.7 years) were recruited. RLS was considered idiopathic in 291 patients (96.4%). Most patients (240, 79.5%) were RLS sufferers, whereas the remaining 62 (20.5%) had RLS as ancillary diagnosis. Nineteen out of 162 patients treated with dopaminergic agents (11.7%) had current augmentation. Almost one-third of all patients (31.1%) had ferritin levels <50microg/l. Patients with an ancillary diagnosis of RLS had higher ferritin levels than RLS sufferers without current augmentation. The lowest ferritin levels were present in RLS sufferers with current augmentation 132.8+/-98.0microg/l vs. 100.6+/-84.5microg/l vs. 55.8+/-43.6microg/l; p=0.002). Patients with augmentation did not differ from non-augmented patients regarding age, gender, RLS etiology, presence of previous augmentation, or any other documented comorbidity (p>0.05).


CONCLUSIONS
The severity spectrum of RLS in this clinical cohort ranged from the ancillary diagnosis of RLS to augmented RLS. There was an inverse correlation between RLS severity and ferritin levels. Patients with current augmentation had the lowest ferritin levels. Our data further strengthen a putative role of low iron stores as a potential aggravator of idiopathic RLS. Moreover, low ferritin might represent a potential biomarker of RLS augmentation under dopaminergic therapy.
Frauscher
Birgit
B
Department of Neurology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
Gschliesser
Viola
V
Brandauer
Elisabeth
E
El-Demerdash
Essam
E
Kaneider
Matthias
M
Rücker
Lukas
L
Poewe
Werner
W
Högl
Birgit
B
D000368:Aged; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D018450:Disease Progression; D015259:Dopamine Agents / Q000008:administration & dosage / Q000009:adverse effects; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D005293:Ferritins / Q000097:blood*; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012148:Restless Legs Syndrome / Q000097:blood / Q000150:complications* / Q000188:drug therapy / Q000503:physiopathology*; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000209:etiology*
D015415:Biomarkers; D015259:Dopamine Agents; D018491:Dopamine Agonists; D007980:Levodopa; D005293:Ferritins