Effect of therapy on the serum thyroglobulin concentration in patients with toxic diffuse goiter, toxic nodular goiter and toxic adenoma

Serum thyroglobulin (S-Tg) was measured in 104 patients with thyrotoxicosis, 59 of whom had toxic diffuse goiter (Graves' disease), in 30 with toxic nodular goiter and in 15 with toxic adenoma. Before treatment, most patients had increased S-Tg concentrations, regardless of what type of thyrotoxicosis they had. After therapy the course of the S-Tg varied, two major patterns being observed: the S-Tg concentration increased in some patients but decreased in others, although no relationship could be found between these patterns and the outcome of therapy, the presence or absence of thyroglobulin antibodies (Tg-ab) or changes in the Tg-ab titer. However, the median pretreatment concentrations of S-Tg were significantly higher in patients with toxic nodular goiter and toxic adenoma than in those with toxic diffuse goiter (p less than 0.001 and p less than 0.05, respectively), but did not differ significantly between patients with toxic nodular goiter and toxic adenoma. The lowest posttreatment S-Tg concentrations were found after surgery, irrespective of type of thyrotoxicosis. The median pretreatment and posttreatment S-Tg concentrations in patients with toxic diffuse goiter who relapsed, did not differ from those patients in remission. This was also true of patients with toxic nodular goiter. In both groups, however, there was a tendency towards higher pretreatment S-Tg values in patients who subsequently relapsed. Serial determinations of S-Tg, on the other hand, are of limited value in predicting the risk of recurrence, independent of which type of thyrotoxicosis is involved.

A radioimmunoassay for human thyroglobulin: methodology and clinical applications

A specific double-antibody radioimmunoassay with a sensitivity of 2.5 ng/ml has been developed for measuring thyroglobulin (Tg) in human serum. As endogenous anti-Tg antibodies in serum interfere in the assay, only sera with a negative tanned red cell (TRC) test are suitable for analysis. Tg was detectable in 84.7% of the euthyroid subjects, with a mean value of 6.1 (values ranging from nondetectable to 43.0 ng/ml). Values were significantly higher in women than in men. Tg release by the thyroid appears to be under pituitary control, as suggested by TSH stimulation and T3 suppression tests. Elevated Tg levels were found in hyperthyroidism, simple goitre, and differentiated thyroid carcinoma. The significance of circulating Tg and the possible application of the Tg RIA are discussed.