Restless Legs Syndrome: An Unresolved Uremic Disorder after Renal Transplantation

BACKGROUND: Restless legs syndrome (RLS) is a common complication of uremia that may improve after transplantation. Its frequency might not be as low as expected, as some uremic disturbances may continue even after a successful graft. Our aim was to investigate the prevalence and related conditions for RLS in renal transplant patients. METHODS: We carried out a cross-sectional, observational study. A self-administered questionnaire following the International Restless Legs Syndrome Study Group diagnostic criteria was administered to 129 patients (82 men and 47 women) aged 57 ± 12.8 years followed up for at least 1 year, with stable renal function (Cr 1.5 ± 0.54 mg/dL). Patients with probable RLS according to the screening questionnaire underwent comprehensive neurological examination to exclude RLS mimics. RESULTS: The frequency of RLS according to questionnaires was 29.5% (18 men/20 women). After neurological exam, RLS was confirmed in 19 patients providing an overall frequency of 14.8% (higher than the prevalence in the general population). A definitive diagnosis of RLS was established for 6 men (7.3%) and 13 women (27.7%), indicating a positive predictive value for the screening questionnaire of 65% for women and 33% for men. There were fewer patients under renin-angiotensin aldosterone system (RAAS) blocking treatment in the RLS group (21.1 vs. 47.3%). Women with RLS had poorer renal function (52 ± 17.5 vs. 42 ± 13.9 mL/min) and phosphate-reabsorption rate (75 ± 10.5 vs. 65 ± 9.2). There was no difference in age, comorbidities, anticalcineurin therapy, renal function, anemia and time since transplantation between transplant patients with and without RLS. CONCLUSION: The prevalence of RLS after transplantation remains high (14.8%). This condition is twice more prevalent for females. Contribution of RAAS, graft function and phosphate overload requires further investigation.