Restless legs syndrome (RLS) is associated with Crohn's disease according to the results of a new study. The authors of this study suggest that RLS could be an extraintestinal manifestation of Crohn's disease.

RLS is a central nervous system (CNS) disorder characterized by an irresistible urge to move the legs at rest—usually to relieve uncomfortable sensations.

RLS can be primary (idiopathic and familial) or secondary. “I decided to look at the subject of secondary RLS and see what kind of diseases and/or disorders have been associated with this condition,” says Weinstock, lead author on the study.

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Crohn's disease and RLS have both been associated with small intestinal bacterial overgrowth and iron deficiency. Weinstock et al. therefore investigated the potential link between these two disorders.

272 consecutive patients with confirmed Crohn's disease completed written questionnaires to prospectively evaluate the presence of RLS. Diagnosis of RLS was made according to four established criteria.

The incidence of RLS (that is, at any point) in patients with Crohn's disease was 43%. The prevalence of RLS (that is, at the time of evaluation) was significantly higher in patients with Crohn's disease compared with control patients (in this case spouses of patients with Crohn's disease). RLS started during or after the onset of Crohn's disease in 91.8% of patients.

“Our conclusion is that RLS occurs frequently in patients with Crohn's disease—the prevalence of RLS in patients with Crohn's disease is higher than for many of the previously known secondary causes of RLS,” says Weinstock.

Weinstock and colleagues hypothesize that inflammation associated with Crohn's disease could increase levels of hepcidin, which affects iron transport. Increased levels of hepcidin could, therefore, lead to iron deficiency in the CNS, possibly resulting in RLS.

“I am in discussions with investigators at Johns Hopkins to see if inflammatory markers can be checked in patients with Crohn's disease and RLS before and after treatment for Crohn's disease, to see if there is a correlation with resolution of RLS,” concludes Weinstock.