Plasma growth hormone profiles and sleep: a study of 13 treated acromegalics

The plasma growth hormone profiles and sleep patterns of 13 treated male acromegalic patients, aged 29-67 years, were studied. All patients had undergone selective pituitary transsphenoidal surgery 4-9 years previously; five patients had also undergone supplemental pituitary irradiation. Blood samples were taken at 20-min intervals; the sleep patterns were obtained by EEG. GH reserve was assessed after insulin-induced hypoglycaemia and GHRH (1-44) with and without pyridostigmine. The profiles were analysed with the aid of the Pulsar program. Seven out of eight non-irradiated patients had 1-3 nocturnal GH peaks; in the irradiated group only one patient had a normal profile. The GH reserve after insulin-induced hypoglycaemia was normal in seven out of eight non-irradiated patients, and subnormal in all five irradiated patients. In the latter group the GH reserve was diminished when tested with GHRH. One patient from each group had a severe apnoea syndrome; in both cases there was no nocturnal GH increase. The percentage sleep stage 1 was lower for irradiated patients when compared with non-irradiated patients, but the 14 other sleep parameters did not differ. From this study we conclude that the physiological regulation of GH secretion is restored in surgically treated patients. Radiation therapy may lead to pituitary and hypothalamic damage, which could affect spontaneous GH secretion.