Restless Legs Syndrome: An Unresolved Uremic Disorder after Renal Transplantation

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.

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.

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.

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.