@article{3149053,
    title = "Effect of Hyperthyroidism on Clearance and Secretion of Glucagon in Man",
    author = "Dimitriadis, G. and Hatziagelaki, E. and Mitrou, P. and Lambadiari, V. and and Maratou, E. and Raptis, A. E. and Gerich, J. E. and Raptis, S. A.",
    journal = "Experimental and Clinical Endocrinology & Diabetes",
    year = "2011",
    volume = "119",
    number = "4",
    pages = "214-217",
    publisher = "JOHANN AMBROSIUS BARTH VERLAG MEDIZINVERLAGE HEIDELBERG GMBH",
    issn = "0947-7349, 1439-3646",
    doi = "10.1055/s-0030-1269880",
    keywords = "endogenous glucose production; insulin resistance; thyroid hormones",
    abstract = "Objective: Glucagon has been proposed to contribute to the increased
glucose production found in hyperthyroidism. However, fasting plasma
glucagon levels are not increased in hyperthyroidism suggesting that the
activity of the alpha-cell is normal. Nevertheless, an increase in the
clearance rate of glucagon may mask increased glucagon secretion. This
study was designed to examine the effects of hyperthyroidism on the
kinetics of glucagon.
Design and methods: A primed-continuous infusion of glucagon was
administered to 9 euthyroid and 9 hyperthyroid subjects at 3 sequential
rates (1200, 3 000 and 6 000 pg/kg/min, each given for 2 h).
Arterialized blood was drawn at 15-30 min intervals for determination of
glucagon.
Results: Fasting plasma glucagon levels were comparable in euthyroids
(195 +/- 8 pg/ml) and hyperthyroids (231 +/- 16 pg/ml). During infusions
(1 200, 3 000 and 6 000 pg/kg/min), plasma glucagon increased to 387 19,
624 44 and 977 +/- 51 pg/ml in euthyroids and to 348 +/- 23, 597 +/- 42
and 938 +/- 56 pg/ml in hyperthyroids respectively. At these infusion
rates, metabolic clearance of glucagon (ml/kg/min) was 6.6 +/- 0.5, 7.4
+/- 0.6 and 7.9 +/- 0.5 in euthyroids and 12.6 +/- 2, 8.9 +/- 1 and 8.8
+/- 0.6 in hyperthyroids, respectively. Metabolic clearance of glucagon
differed between hyperthyroids and euthyroids at 1 200 pg/kg/min
infusion rate (p=0.001). The basal delivery rate of glucagon (ng/kg/min)
was 1.3 +/- 0.1 in euthyroids and 2.9 +/- 0.6 in hyperthyroids
(p=0.0005).
Conclusions: In hyperthyroidism, the secretion and metabolic clearance
rates of glucagon are increased. These effects may explain the changes
in plasma glucagon levels observed in hyperthyroidism and support the
important role of glucagon in increasing endogenous glucose production
in this condition."
}