Secretion of ghrelin, which stimulates appetite,
is decreased in hyperthyroidism
(March 2003)
The background
of the study. Ghrelin is a hormone produced by the
stomach that acts in the brain to stimulate appetite. Many patients
with hyperthyroidism lose weight and have an increase in appetite,
which might be caused by increased ghrelin production. In this study,
serum ghrelin was measured in patients with hyperthyroidism before
and during treatment.
How the study was done.
The study subjects were nine women with hyperthyroidism caused by
Graves' disease and nine normal women. The women with hyperthyroidism
were studied before and after treatment with an antithyroid drug,
and the normal women were studied once. Serum ghrelin, leptin, insulin,
and other substances were measured after an overnight fast. Body
composition and energy expenditure were also measured.
The results of the study.
The average weight of the women with hyperthyroidism was 59 kg before
and 64 kg after treatment; the normal women weighed 70 kg. The women
with hyperthyroidism had less fat tissue and a lower lean body mass
than the normal women, and both values increased during antithyroid
drug treatment. Their estimated energy expenditure was 52 kcal/day/kg
of lean body mass before treatment and 38 kcal/day/kg of lean body
mass after treatment, as compared with 34 kcal/day/kg of lean body
mass in the normal women.
The mean fasting serum ghrelin concentration was lower in the women
with hyperthyroidism than in the normal women (1080 vs. 1870 pg/ml);
it increased (1480 pg/ml) after antithyroid drug treatment. There
were no differences between the fasting serum concentrations of
leptin, insulin, glucose, and fatty acids in the women with hyperthyroidism
and the normal women.
The conclusions of the study.
Serum concentrations of ghrelin are lower in women with hyperthyroidism
than in normal women, indicating that the increase in appetite in
hyperthyroidism is not caused by ghrelin.
The original article.
Riis AL, Hansen TK, Moller N, Weeke J, Jorgensen JO. Hyperthyroidism
is associated with suppressed circulating ghrelin levels. J Clin
Endocrinol Metab 2003;88:853-7.
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