[Detection of recurrence in patients with differentiated epithelioma of the thyroid]

Two complementary methods are available for detection of tumour recurrence in patients with treated differentiated thyroid carcinoma: plasma thyroglobulin (Tg) measurement and I 131 total body scans (TBS). Tg is measured during T4 treatment: in patients with no thyroid tissue, detectable Tg levels indicated relapse requiring localisation by TBS. False negative results are rare but have been reported and therefore, it is useful to repeat Tg measurement after TSH stimulation in patients with undetectable Tg levels during T4 treatment. Patients with residual thyroid tissues and an elevated Tg level probably have tumour recurrence, but in most cases, Tg is within normal limits and no conclusions can be drawn. TBS in patients with no thyroid tissue is performed 2 weeks after withdrawal of T3. Patients with residual thyroid tissue have TBS performed after 3 injections of bTSH. Doses of 1 to 5 mCi of I 131 are given and TBS is carried out 3 days later? In conclusion, we can say that these two methods are complementary: Tg levels indicate the need for TBS.