Restless legs syndrome (RLS) is one of the potential neurologic complications associated with CKD or ESRD, though it can also occur independently of kidney dysfunction, with some cases of familial transmission documented (though no gene has yet to be identified). The 2003 NIH criteria for the diagnosis of RLS are the following:
(1) the urge to move the legs, usually with unpleasant sensations.
(2) the appearance of symptoms during inactivity or rest.
(3) relief of symptoms with movement.
(4) worsening of symptoms in the evening or at night.
The mechanism of RLS is unclear, but many signs point to (a) the dopaminergic system (dopamine agonists, such as ropinirole, have been observed to successfully treat some individuals with RLS), and (b) iron status (iron supplementation also appears to have some benefit in treating RLS in individuals with depleted iron stores–a problem which may be accentuated in dialysis patients). In addition, there is some suggestion that inadequate dialysis may be a cause of RLS; this study by Kim et al showed that pre-dialysis BUN is associated with RLS symptom severity.
Thus the workup for dialysis patients with RLS symptoms should include an assessment of dialysis adequacy, review of anemia/iron labs, review of the medication list for drugs which have been associated with RLS (certain antidepressants and antipsychotics have been implicated), and any evidence of a positive family history of RLS.