Circadian periodicity of plasma prolactin in some neurological diseases.

The circadian rhythmicity of plasma PRL has been studied in some neurological diseases in which hypothalamic involvement or abnormalities of brain neurotransmitters has been postulated. 11 patients with Steinert's myotonic dystrophy, 7 with cluster headache and 10 with Huntington's chorea have been studied. By the mean cosinor procedure, a significant circadian rhythm of plasma PRL has been observed both in Steinert's disease and in cluster headache, whereas a circadian periodicity is not detectable in Huntington's chorea, a degenerative disorder affecting the basal ganglia, the hypothalamus and many other areas of the CNS.