Spontaneous pituitary-thyroid function after surgical treatment of nontoxic goitre. A controlled long-term study.

The free thyroxine index (FT4I), triiodothyronine (T3) and thyroid stimulating hormone (TSH) in serum and the peak serum TSH (TRH test) were measured in 18 patients with nontoxic uninodular goitre and 32 patients with nontoxic multinodular goitre before and 3, 6, 12, 24 and 36 months after goitre resection. Thyroid hormone therapy was not given postoperatively. Resection of non-toxic goitre provoked a transient rise in TSH baseline level, with peak about one year after surgery. Three years after the resection the TSH baseline had returned to the preoperative level. The TSH changes were significantly more pronounced in the multinodular goitrous group, in which resection was bilateral, than in the uninodular goitrous group. The changes in serum FT4I and serum T3 were of moderate degree and most pronounced in the multinodular group. During long-term observation, serum FT4I increased slightly but significantly in both groups, but serum T3 showed significant reduction, albeit within reference range. The results of the study suggest that thyroid hormone therapy as a routine procedure after simple goitre resection lacks a tenable rational basis.