Glucose metabolism of the thyroid in autonomous goiter measured by F-18-FDG-PET

The radiolabeled glucose analogue F-18-Fluoro-Deoxy- glucose (F-18-FDG) and Positron Emission Tomography (PET) were used to measure glucose metabolism of the thyroid in vivo. We evaluated patients with autonomous goitre befor e therapy with radioiodine in comparison to patients with normal thyroids. 30 patients with autonomous goitre underwent scanning the day before radioi odine therapy. 19 patients with head or brain tumours and normal thyroids w ere the controls. Overall F-18-FDG uptake was determined for all thyroids a nd proved to be significantly higher in autonomy patients compared to contr ols and in disseminated autonomous goitre slightly but not significantly hi gher than in focal autonomy. In autonomy patients F-18-FDG uptake increased with increasing radioiodine uptake and shorter radioiodine half-life. These results indicate that glucose metabolism is enhanced in the thyroids of patients with focal and disseminated autonomy. The negative correlation of radioiodine half-life and glucose metabolism as well as the positive cor relation of radioiodine uptake and glucose metabolism suggest connections o f glucose metabolism and iodine-dependent hormone synthesis in thyroid cell s.