1977 Volume 20 Issue 1 Pages 76-81
Plasma glucagon levels were studied in 11 patients with acromegaly and in 14 patients with isolated growth hormone deficiency. As controls, 20 normal sudjects and 7 normal children were examined. Acromegalic patients were divided into two groups ; one with diabetes mellitus, and the other without diabetes mellitus.
After overnight fasting and absolute bed rest for at least 30 min, all subjects received an intravenous infusion of 30 g or 0.6g/kg of L-arginine over a period of 45 min, All acromegalic patients and 12 normal subjects were also given orally 50 g of glucose. Plasma glucagon was determined by the talcum radioimmunoassay, using antiserum 30 K which is specific to pancreatic glucagon.
Fasting plasma glucagon levels in patients with acromegaly and isolated growth hormone deficiency were 18138pg/ml, 175+21pg/m/, respectively, which were significantly higher than those in the control subjects. In acromegalic patients, plasma glucagon response to arginine was significantly higher than in normal subjects. Plasma glucagon increase induced by arginine was not significantly higher in acromegalic patients with diabetes mellitus than in those without diabetes mellitus. Arginine-induced glucagon secretion in patients with isolated growth hormone deficiency was significantly higher than in normal children. This indicates that both excessive secretion of growth hormone and growth hormone deficiency cause glucagon hypersecretion.
Following oral glucose loading, plasma glucagon decreased successively in normal subjects, whereas it did not decrease and rather tended to be paradoxically elevated in patients with acromegaly. This phenomenon was more remarkable in the patients with diabetes mellitus.
These results suggest that growth hormone is probably required for optimum function of the islets and that excessive growth hormone will cause excessive glucagon secretion which may contribute to the diabetic diathesis in acromegaly. Since hyperglucagonamia was observed in growth hormone deficiency, some other factors influenced by growth hcrmone may affect glucagon secretion.
The significance and pathogenesis of hyperglucagonemia in these conditions are still unclear at present and must await further clarification.
