[Studies on the reliability of the 99mTc-uptake as a measure of thyroidal stimulation (author's transl)].

In 44 patients with stimulated goitre the trapping kinetics of 131I-iodide and 99mTc-pertechnetate are analyzed having corrected for different size of the thyroid and different physical properties of the tracers under use. Unidirectional iodide clearance (UDCL) is chosen as reliable estimator of thyroidal stimulation. UDCL shows strong correlation to iodide uptake tests and the correlation to pertechnetate uptake tests is sufficiently strong for semiquantitative evaluation of thyroidal stimulation. Under the conditions of clinical routine work the reproducibility of pertechnetate uptake tests exceeds that of iodide, thus, pertechnetate uptakes are more suitable for evaluation of regulation tests, i.e. suppression test and stimulation test with TSH. 99mTc-thyroid-uptake (TcTU) 20 min after injection is a useful parameter of thyroidal stimulation for clinical routine work as it combines excellent reproducibility with strong correlation to unidirectional iodide clearance as the relevant parameter of thyroidal stimulation.