Iron metabolism and the risk of Restless Legs Syndrome in an elderly general population - The MEMO-Study

Background Low iron and ferritin blood levels have been observed in patients with Restless Legs Syndrome (RLS) with an inverse relation between symptom severity and ferritin level. All reports are based on single cases or case series of hospitalized patients or those from outpatient clinics. No data from population studies are available. Methods Cross-sectional study examining the associations between 5 measures of iron metabolism and RLS in an elderly general population in southern Germany. All 365 participants, aged 65 to 83 years, were examined neurologically and interviewed using standardized questions addressing the four minimal criteria for RLS. Iron, ferritin, transferrin, soluble transferrin receptor and C-Reactive Protein were analysed with standard laboratory methods. Results The prevalence of Restless Legs Syndrome in this population was 9.8%. Odds Ratios associated with Restless Legs were significantly increased in the fourth quintile of iron (OR 3.08 95% Cl 1.02-9.29) and transferrin saturation (OR 5.68 95% CI 1.18-27.26) compared with the third (middle) quintile. Increases in the first (lowest) quintile of both measures were not or borderline significant. No associations with ferritin and soluble transferrin receptor were found. Conclusions No evidence was found that iron or ferritin deficiency are a major cause of RLS in this population study. The results support the hypothesis that changes in the complex regulation of iron metabolism contribute to the occurence of RLS.