The incidence of antithyroglobulin autoantibodies (ATA) was 17.7% in 963 patients (who attended the clinic from 1981 to 1990) with differentiated thyroid carcinoma (DTC). Another 12 patients developed ATA for a transient period after the treatment with radioiodine. The prevalence of ATA in females (21.5%, 123/572) was significantly higher (p < 0.001) than that seen in males (12.0%, 47/391). Age-dependent occurrence of ATA was not seen for the various age decades. The ATA was more prevalent (p < 0.01) with the papillary type of tumor (118/564) as compared to the follicular variety (51/398). ATA did not influence the metastatic spread of the tumor at the initial presentation (105/170 for the ATA-positive group and 445/793 for the ATA-negative group). However, within the group with metastases, 82.9% (87/105) of patients had local spread into the neck in the presence of ATA, which was significantly higher (p < 0.01) than that seen for patients without ATA (63.8%, 284/445). For assessment of the influence of ATA on the outcome of the disease, the data from 222 patients (46 positive and 176 negative for ATA), with a minimum follow-up of 5 years (mean follow-up of 7.4 years), was considered suitable for analysis. The outcome of the disease was comparable in the presence and the absence of ATA (38/46 and 137/176 patients became disease-free in ATA-positive and -negative groups, respectively). Of the 46 patients with circulating ATA, antibodies disappeared or decreased in all 38 patients who became disease-free as compared to 8 patients (p < 0.001) with persistent disease; ATA disappeared in 5 but remained unchanged in 3 of these patients. From this study we conclude (a) ATA is more prevalent in females and in papillary type of tumors, (b) the occurrence of ATA in patients with DTC is not age dependent, (c) the presence of ATA does not restrict or promote the metastatic spread of the tumor, (d) there is a tendency for local metastases in the presence of ATA, (e) ATA does not protect or worsen the progress of the disease, and (f) the persistence of antibodies is indicative of functioning thyroid tissue.
