Aim: Gain-of-function mutations of the thyrotropin receptor (TSHR) gene have been invoked as one of the major causes of toxic thyroid adenomas. This study evaluates F-18-FDG-PET in these patients.
Methods: Twenty patients with focal autonomous nodules and ten with disseminated autonomy were investigated the day before radioiodine therapy. Twenty patients with cancer of the head or neck and normal thyroid function served as controls.
Results: F-18-FDG-Uptake was higher in patients than in controls. Focal autonomous nodules were associated with focally enhanced glucose metabolism. Disseminated autonomous goiters showed various patterns of focal or global hypermetabolism.
Conclusion: Autonomous thyroid tissue caused by constitutive mutations of the TSH receptor is characterised by simultaneous increases in glucose and iodine metabolism which are correlated.