Nocturnal urinary dopamine excretion is reduced in otherwise healthy subjects with periodic leg movements in sleep.

The pathophysiology of periodic leg movements (PLMs) in sleep remains to be elucidated. Among other hypotheses an alteration of dopaminergic function has been suggested. Nocturnal urinary dopamine and 4-hydroxy-3-methoxyphenylacetic acid excretion in otherwise healthy subjects with PLMs was significantly reduced (P < 0.001 and P < 0.05, respectively) compared to subjects without PLMs. This finding, for the first time, demonstrates a correlate of a functionally relevant hypoactivity of the dopaminergic system in subjects with PLMs.