Thyroid function test in suspected focal or diffuse autonomy in peripheral euthyroidism and unsuppressed basal TSH(thyroid stimulating hormone).
For complete suppression of basal TSH production, thyroid hormones are first administered for 8-14 days (e.g. 60-100 μg liothyronin/day for 8-10 days, 150-200 μg levothyroxin/day for 14 days).
Immediately before the scintigraphic examination, determination of the basal TSH value. Subsequently, a thyroid scintigraphy is performed.
Assessment: If "hot" areas persist, a functionally relevant autonomy is ensured.