Restless Legs Syndrome

Primary and Secondary RLS

Primary RLS has been identified as having a more insidious onset of symptoms, which occur at an earlier age (usually before 40 years); patients with primary RLS are more likely to have affected family members than are people in the general population or even those patients with the secondary form of RLS.9-12In secondary RLS, the onset is usually more precipitous and typically occurs after age 40 years.13 In this case, RLS occurs in relationship to other conditions, such as pregnancy,14-23 end-stage renal disease (ESRD),24-42and iron deficiency (with or without anemia)43-50 or with the use of medications, such as dopamine receptor antagonists,51-58 histamine-receptor antagonists,59 and antidepressant drugs.60-63

Patients with a late age of onset of symptoms are also less likely to have decreased serum ferritin levels, as compared with patients with early-onset RLS.13 Children and adults with RLS often exhibit symptoms of attention-deficit hyperactivity disorder (ADHD).64-68 Whether this occurs because of the impact of RLS on sleep or an overlapping dopaminergic dysfunction is not known.65,68-70 In children, symptoms of RLS are frequently mislabeled as growing pains.10,71-76