Food Choice in Hyperthyroidism: Potential Influence of the Autonomic Nervous System and Brain Serotonin Precursor Availability

We explored energy and macronutrient intake in patients with Graves’ hyperthyroidism. We specifically hypothesized that hyperthyroidism is associated with increased appetite for carbohydrates, because of enhanced sympathetic tone and diminished serotonin mediated neurotransmission in the brain. To test this hypothesis, we measured food intake by dietary history and food selected for lunch in the laboratory in 14 patients with Graves’ hyperthyroidism. Twenty-four-hour catecholamine excretion was used as a measure of activity of the sympathetic nervous system (SNS) and the plasma [Trp]/[NAA] ratio was measured to estimate (rate limiting) precursor availability for brain 5-hydroxytryptamine synthesis. All measurements were repeated after the subjects had been treated to establish euthyroidism. In addition, the effects of nonselectiveβ -adrenoceptor blockade upon these parameters were studied to evaluate the influence of β-adrenergic hyperactivity on food intake. Hyperthyroidism was marked by increased SNS ac...