Follow-up regimen of differentiated thyroid carcinoma in thyroidectomized patients after thyroid hormone withdrawal

For differentiated, nonmedullary thyroid carcinoma, postsurgical ablation o f thyroid remnants and treatment of residual tumor and metastases with I-13 1 is a potentially curative therapy. The aim of this study was to optimize the diagnostic protocol for the follow-up of thyroidectomized patients. Met hods: Two hundred fifty-four patients (187 females, 67 males; mean age, 45 y; range, 8-83 y) were studied retrospectively for a mean follow-up period of 2.7 y (range, 1-12.5 y). An evaluation study consisted of a low-dose I-1 31 diagnostic procedure under hyperthyroid conditions (thyroid-stimulating hormone > 30 mu U/mL), (TI)-T-201 scintigraphy, and measurement of thyroglo bulin (Tg) under hypothyroid conditions. A total of 254 preablation studies (1 study per patient) and 586 follow-up studies (average number of studies , 2.3 per patient) were evaluated. Results: Before ablation, low-dose I-131 screening was useful to estimate the size of the thyroid remnant. Low Tg l evels (<10 pmol/L) indicated the absence of metastases, After ablation, und etectable Tg levels indicated the absence of tumor recurrence. When Tg leve ls were high (>10 pmol/L), local recurrence or metastases were always obser ved, providing the basis for additional high-dose I-131 therapy. In these p atients, (TI)-T-210 imaging did not provide a significant contribution to p atient management. In the case of autoantibodies against Tg, both low-dose I-131 screening and (TI)-T-201 scintigraphy may be advocated to allow an ag gressive diagnostic work-up. Conclusion: Tg plays a key role in follow-up a nd in making decisions to treat patients with differentiated thyroid carcin oma. The role of (TI)-T-201 imaging is very limited. In patients with negat ive low-dose I-131 screening, (TI)-T-201 scintigraphy can be considered whe n Tg is elevated or cannot be evaluated because of autoantibodies against T g. Under such circumstances, administration of a therapeutic I-131 dose wit hout (TI)-T-201 imaging can be considered.