The influence of subtotal thyroidectomy on the thyroglobulin binding capacity of thyrotoxic serum.

It has been shown previously that large amounts of thyroglobulin are released into the circulation by the trauma of thyroid surgery. In order to characterize the response to this challenge in patients with and without autoimmune disease, serial estimations of thyroglobulin binding capacity (AgBC) using a sensitive double antibody technique were made on 105 patients undergoing partial thyroidectomy for thyrotoxicosis (70 patients prepared medically) and nontoxic goiter (35 patients). Samples were measured the day before, the day of, and on eight subsequent occasions during the first 14 days after surgery. Three distinct patterns of change in AgBC were observed in the thyrotoxic patients: i) when elevated before surgery, it fell acutely within 48 h of operation and rose again within the first 7-10 days (8 patients); ii) it rose briskly, though transiently, when low (less than 10%) before surgery (4 patients); iii) when elevated before surgery, it rose or fell gently afterwards without sudden change (7 patients). The AgBC in 51 of the Graves' disease patients never exceeded 10% during the perioperative period, and was immeasurably low in all nontoxic goiter patients. Autoimmune thyroid disease results from a disturbance of normal tolerance to thyroid antigens, and thyroid surgery provides an in vivo model in which the response to an acute antigenic challenge may be studied. Patients with Graves' disease showed varying degrees of intolerance to the challenge, while those with nontoxic goiter and no evidence of autoimmune disease were uniformly unresponsive.