Serum thyroglobulin in thyroid carcinoma and other thyroid disorders

Abstract

Measurements of serum thyroglobulin (hTg) were performed using a specific radioimmunoassay. Sera with detectable anti-thyroglobulin (anti-Tg) antibody titers (>1∶10) as assessed by passive hemagglutination were discarded. Assays were carried out under conditions in which anti-Tg titers less than 1:10 produced no interference. The assay sensitivity was 1.25 ng/ml and the mean ± SE concentration of serum hTg in 58 control subjects was 9.5 ± 0.9 ng/ml (range< 1.25–27 ng/ml). A slight but significant (p131| whole body scan. A slight but significant (p < 0.0005) increase in the mean concentration of hTg was observed in nonthyroidal malignancies (21.7 ±4.5 ng/ml; n = 10). Serial measurements showed a transient increase of serum hTg after¹³¹| therapy of differentiated thyroid carcinoma, toxic diffuse goiter or toxic adenoma, with peak values usually occurring within the first three days. A fall of serum hTg after administration of suppressive doses of thyroid hormone to patients with nontoxic goiter and a rise after discontinuation of thyroid suppressive therapy in patients with metastatic differentiated thyroid carcinoma was observed. The present data confirm and extend previous data indicating that serum hTg is frequently elevated in thyroid disease, and that the release of hTg from malignant and nonmalignant thyroid tissue is at least in part thyrotropin (TSH) dependent and it is enhanced by radioiodine therapy. Measurements of serum hTg do not differentiate from benign and malignant thyroid disease, but may be usefullly employed in the follow up of differentiated thyroid carcinoma. Of particular interest was the finding that nonfunctioning metastases may be detected by measurement of serum hTg and that bone or lung metastases are associated with much higher levels of serum hTg than lymph node metastases.