BACKGROUND: Serum thyroglobulin determination has been reported to be a sensitive indicator of recurrent differentiated thyroid carcinoma. The purpose of this study is to determine the accuracy of serum thyroglobulin levels in predicting tumor recurrency after parcial thyroidectomy. METHODS: Forty eight patients with differentiated thyroid carcinoma were followed with serum thyroglobulin measurement after parcial thyroidectomy. Patiens recived hormonal suppressive therapy to maintain plasma TSH level below 0,6 mU/cc. Mean follow-up was 8,1 years. Serum thyroglobulin level above 10ng/cc was considered suspect of tumor recurrency. RESULTS: Eleven patients showed serum thyroglobulin level above 10 ng/cc. In four of them, elevations were considered spurious (hiparthyroidisme - 2 cases, and Hashimoto disease - 2 cases) and were excluded from statistical analysis. In the other 7, tumor recurrence was demonstrated in 6 (true positive: 6; false positive: 1). In 37 patients with low thyroglobulin level, only 1 had recurrence (true negative: 36; false negative: 1). Statistical analysis show sensibility 85%, specificity 94%, positive predictive value 85%, negative predictive value 84% and accuracy 95%. CONCLUSIONS: Serum thyroglobulin determination is an useful test to identify patients with persistent or recurrent differenctiated cancer, inicially submited to parcial thyroidectomy.
Thyroglobulin; Differentiated carcinoma; Parcial thyroidectomy