Serum thyroglobulin in the investigation of patients presenting with metastases

Serum thyroglobulin (Tg) is often very elevated in patients with metastatic thyroid carcinoma and, in 18 out of 40 patients examined, serum Tg was found to exceed 400 micrograms/l. In only two of 55 patients with benign nodular thyroid disease did serum Tg exceed 400 micrograms/l. In patients presenting with metastases of unknown origin, the finding of a very elevated serum Tg concentration may therefore be of value as an indicator that the metastases are due to thyroid carcinoma. During a period in which 128 new patients with differentiated thyroid carcinoma were seen, in five who presented with metastatic disease the initial estimation of serum Tg had proved useful in suggesting the thyroid origin of the metastases.