Insulin levels in thyrotoxicosis and primary myxoedema: Response to intravenous glucose and glucagon

Abstract

Summary. Glucose disappearance, insulin-like activity (ILA) and serum immunoreaetive insulin (Ii%I) were studied after intravenous injection of glucose or glueagon in patients suffering from thyrotoxieosis or primary myxoedema. A group of normal subjects was also investigated. Glucose disappearance rate appeared to be normal in hyperthyroid, and markedly reduced in hypothyroid subjects. Fasting ILA levels were significantly higher than normal in myxoedema, and lower than normal in thyrotoxicosis. On the other hand, fasting I1:r levels were higher than normal in myxoedema but normal in thyrotoxieosis. After glucose administration I LA in myxoedema remained at higher values than in thyrotoxieosis at any time of the study; in myxoedema, peak ILA levels were reached later than in thyrotoxieosis ; peak I1%1 levels of similar magnitude were reached slightly earlier than normal in thyrotoxicosis, and later in myxoedema; in the latter condition, elevated IgI levels were observed for a longer period than in either euthyroidism or hyperthyroidism. During this test the insulingogenic index showed only slight changes in normal and in thyrotoxie subjects, whereas it increased significantly up to 60 rain in myxoedema. The data indicate that the reduced glucose utilization in hypothyroidism is not due to insulin deficiency, but rather to insulin resistance. It also seems possible that thyroid function influences the time of maximal insulin response to intravenous glucose administration. After glueagon injection, the increase in blood glucose was lower and shorter than normal in thyrotoxieosis; it was initially somewhat slower, but later higher and more sustained than normM, in myxoedema. The smaller increment in blood glucose in the former condition is probably eormeeted with reduced glycogen stores. ILA response was very high and well sustained in myxoedema, whereas it was moderate and shortlasting in thyrotoxieosis. Ii%I response was higher than normal in hypothyroid subjects, and lower than normal in thyrotoxie subjects. No difference in the time required for maximal response was observed among the three groups.

Insulin delivery rate in response to glucose and arginine infusion in hyperthyroidism

“…In hyperthyroidism, therefore, glucose intolerance appears to be primarily related to an antagonism of the hepatic effect of insulin by thyroxine rather than an inhibitory effect of thyroxine on insulin secretion. However, since delivery rate represents the measurement of peripheral serum insulin concentrations, these results cannot exclude an abnormality of hepatic insulin metabolism in hyperthyroidism.Key words: Insulin delivery rate, insulin secretion in hyperthyroidism, glucose, arginine, insulin disappearance rate.Glucose tolerance and insulin secretion have been examined extensively in hyperthyroidism [1][2][3][4], and a reduced glucose tolerance has been found in patients with this condition [2,3]. However, intravenous glucose infusions in hyperthyroid men or dogs have produced conflicting results concerning plasma insulin secretion [2][3][4][5].…”

“…However, intravenous glucose infusions in hyperthyroid men or dogs have produced conflicting results concerning plasma insulin secretion [2][3][4][5].…”

“…Glucose tolerance and insulin secretion have been examined extensively in hyperthyroidism [1][2][3][4], and a reduced glucose tolerance has been found in patients with this condition [2,3]. However, intravenous glucose infusions in hyperthyroid men or dogs have produced conflicting results concerning plasma insulin secretion [2][3][4][5].…”

Insulin Secretion in Patients with Hyperthyroidism: in Relation to Abnormalities in Carbohydrate Metabolism

“…The reason for this may be attributed to the different species studied: man (Amatuzio et al, 1954;Lamberg, 1965;Woeber et al, 1966;Doar et al, 1969;Levy et al, 1970;Andreani et al, 1970;Cavagnini et al, 1974;Andersen et al, 1977), rat (Malaisse et al, 1967), dog (Renauld et al, 1975), and rabbit (Marecek and Feldman, 1973). It may also be attributed to different secretagogues used for insulin secretion: glucose (Amatuzio et al, 1954;Woeber et al, 1966;Doar et al, 1969; Endocrinol.…”

“…August1979 Andreani et al, 1970;Cavagnini et al, 1974), tolbutamide (Andersen et al, 1977), glucagon (Levy et al,, 1970), and arginine (Cavagnini et al, 1974;Seino et al, 1974). IVGTT, and11out of34with IVTT were reexamined soon after they had been made euthyroid.…”