The effects of calcitonin, somatostatin and hypercalcaemia on metabolic and hormonal indicators during an oral glucose tolerance test (OGTT).

Abstract

The authors compared the effect of synthetic salmon calcitonin and synthetic somatostatin (SRIF) and hypercalcaemia on an oral glucose tolerance test (OGTT) in healthy subjects in relation to changes of insulin (IRI), somatotrophin (HGH) and cortisol levels. Calcitonin--100 U--in an intravenous infusion in the course of OGTT markedly altered the pattern of the blood sugar curve and of IRI levels. After the initial retardation of the rise of the blood sugar and IRI levels during the 15th and 30th min, the values of both variables increased parallel during the 120th and 180th min, as compared with the control examination after saline. SRIF--500 micrograms--administered in an intravenous infusion altered the pattern of the blood sugar and IRI curves in a similar way as calcitonin, however during the 120th and 180th minute when the blood sugar levels rose significantly the IRI levels did not rise. The curve of HGH levels on infusion with calcitonin displayed a typical three-phase course, as during the control OGTT. During infusion of SRIF the HGH levels were insignificantly but constantly reduced during the first 60 mins. of the OGTT and thus the typical three-phase shape of the curve was impaired. Calcitonin significantly raised the cortisol levels throughout the OGTT, while SRIF caused their slight decline during the 120th min. Hypercalcaemia induced by infusion of 13.3 mg Ca/kg body weight did not alter significantly the blood levels of glucose, IRI and HGH, but caused a significant rise of the cortisol level throughout the OGTT.(ABSTRACT TRUNCATED AT 250 WORDS)