[Diagnosis of hyperthyroidism]

The clinical signs and symptoms of the patient are the background for further examination procedures. A dysfunction of the thyroid gland can be safely excluded when the TSH level is within the normal range. A hyperthyroidism can be proven when TSH is suppressed and T3 and T4 levels, respectively, are elevated. However, the concentrations of T3, T4 (inclusive free T3 and free T4) and TSH are not only dependent on the thyroid status, but also on various extrathyroidal influences. Therefore awareness of accompanying diseases and of medications is necessary in order to avoid errors of interpretation. Different forms of hyperthyroidism have to be distinguished. The differentiation between Graves' disease and the functional autonomy (toxic nodular goiter) is of practical importance. Several methods--apart from precise clinical examination--are helpful. When Graves' disease is suspected TSH-receptor- and TPO-antibodies should be measured and an ultrasound obtained. When an autonomy is suspected, a szintigraphy as well as ultrasound should be undertaken. The laboratory methods are of high precision and sensitivity. There use is dependent on the clinical diagnostic problem, which also determines the extend and expenditure of the diagnostic procedures. These considerations are necessary also for economical reasons.