Analysis of functional autonomy in euthyroid goitre.In an area of moderate iodine deficiency 163 goitrous patients without and 179 with functional autonomy all clinically euthyroid were compared by sex, age, signs and symptoms, sonographic results, qualitative and quantitative scintigraphy without and with suppression, TRH test, hormone concentrations and iodine excretion in the urine.Age, signs and symptoms, thyroid volume and structure did not contribute sufficiently to diagnosis. To detect functional autonomy quantitative scintigraphy under suppression was superior to the TRH test. Increased hormone concentrations were observed in 15% of patients with functional autonomy. A global 99mTc thyroid uptake of > or = 3% under suppression indicates a higher risk of spontaneous hyperthyroidism. It was present in 20% of patients with functional autonomy.To diagnose and treat adaequately functional autonomy in euthyroid goitre quantitative scintigraphy, determination of TSH and hormone concentrations are inevitable.