Study on growth hormone and prolactin secretions in myotonic dystrophy.

Basal and stimulated GH and PRL secretions have been studied in four patients with myotonic dystrophy. High values of basal plasma GH have been occasionally found in two patients. Abnormal plasma GH responses were coexisting with normal ones after each stimulus (oral l-dopa, oral glucose load, arginine infusion, i.v. insulin, i.v. metoclopramide). Basal plasma PRL levels were normal in all patients as well as responses to different stimuli except the response to insulin-induced hypoglycaemia that was abnormal in three patients out of four. It is concluded that in myotonic dystrophy hypothalamic regulatory mechanisms of pituitary functions may be altered because of known thalamic lesions or yet unrecognized hypothalamic ones.