Study on growth hormone and prolactin secretions in myotonic dystrophy

Basal and stimulated GH and PRL secretions were studied in 4 patients with myotonic dystrophy. High values of basal plasma GH were occasionally found in 2 patients. Abnormal plasma GH responses coexisted 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 hypoglycemia that was abnormal in 3 patients out of 4. It is concluded that in myotonic dystrophy hypothalamic regulatory mechanisms of pituitary functions may be altered because of known thalamic lesions or, as yet, unrecognized hypothalamic ones.