Clinical and biochemical findings in uremic patients with and without restless legs syndrome

The restless legs syndrome (RLS) is one of the most common and unpleasant complaints of uremic patients. The pathophysiology of the RLS is still unclear. Various factors, including anemia and iron deficiency, are proposed to play a major role. We determined the prevalence of RLS in all stable hemodialysis patients under long-term treatment in two dialysis centers (n = 136) and compared the clinical and biochemical findings of patients with RLS and without RLS. Twenty-three percent of all patients investigated fulfilled the diagnostic criteria of RLS according to the International Restless Legs Syndrome Study Group. There were no statistical differences between the two groups regarding age, duration of uremia and need for dialysis, time on dialysis per week, hemoglobin, hematocrit, erythrocytes, s-ferritin, s-transferrin, s-iron, calcium, and standard biochemical indices, except for intact parathyroid hormone (iPTH) levels. Uremic patients with RLS showed significantly lower iPTH (P < 0.01) concentrations. In addition, the RLS group received a significantly higher number and dosage of psychopharmacological drugs, (ie, L-DOPA), than patients without RLS. These biochemical findings suggest that neither the severity of anemia nor that of iron deficiency has to be considered a major pathophysiological factor in established RLS. The significantly lower iPTH secretion in uremic patients with RLS, however, is a new finding, and further investigations will be necessary to determine whether this result is of any clinical significance to this group of patients. The significantly higher number of psychopharmacological drugs prescribed to uremic patients with RLS may be related to the symptoms of RLS.