RESUMO
AIM: In 76 patients with thyroid carcinoma (60 f., 16 m.; age 51 +/- 15 years; 52 with papillary, 22 with follicular, 2 with Hürthle cell thyroid carcinoma), three different schemes to withdraw LT4 before 131I whole body scintigraphy were compared. METHOD: In scheme I no interval LT3 medication is applied. Scheme II starts one week after withdrawal of LT4 with a two weeks lasting LT3 medication: 40-80 micrograms LT3/die in the first week and 20 micrograms LT3/die in the second week. Afterwards no further LT3 medication is given. Scheme III is identical to scheme II in the first three weeks but 20 micrograms LT3 medication is continued until 131I-application. Retrospectively 121 studies were evaluated concerning the scheme specific increase of TSH. Factors which may influence the increase of TSH were analysed, i.e. age, sex, thyreoglobuline, LT4 dose, duration of LT4 treatment, histological type of carcinoma, result of 131I whole body scanning. RESULTS: There was a significant relation between increase of TSH and the applied scheme. Schemes with interval LT3 medication are more comfortable for the patient but time to stimulate TSH to values > or = 30 microIU/ml is prolonged, especially using scheme III. Female patients needed a significantly longer time compared to male patients to reach a TSH value > or = 30 microIE/ml. Concerning repetitive withdrawal of LT4, there was a fair intraindividual reproducibility of the time period from LT4 withdrawal to TSH values > or = 30 microIE/ml. CONCLUSION: Every scheme has its specific field of indication depending on the compliance of the patients.
