[Rational diagnosis of disorders of thyroid function].

A. A dysfunction of the thyroid gland can be safely excluded when the local finding of the thyroid gland, perhaps including an ultrasound, is normal and the TSH-levels are unchanged (between 0.4 and 4.0 microE/ml). B. A hyperthyreosis can be proven in 98% when TSH is suppressed (possibly a negative TSH-test) and the T3 levels and the FT3 levels, respectively, are elevated. Following examinations are necessary for the further diagnostics: When a Base-dow hyperthyreosis is suspected, T4, TR and TPO antibodies should be measured and an ultrasound obtained. When a focal or disseminated autonomy is suspected, a scintigraphy and suppression scintigraphy, respectively as well as an ultrasound should be undertaken. C. A hypothyreosis can be proven in 98% when TSH is elevated (possibly an overshooting TSH test), and the T4 levels are low. For further diagnostics, ultrasound and maybe scintigraphy should be undertaken in case of a congenital hypothyreosis. In case of an acquired hypothyreosis, TR and TPO antibodies should be measured, an ultrasound obtained, and a cytology might be taken to exclude a thyreoiditis De Quervain or a Hashimoto thyreoiditis.