Thyroid function following partial thyroidectomy

The main objective of this investigation was to establish the incidence of hypothyroidism and recurrent goitre following partial thyroidectomy. Accurate measurements of the thyroid remnants and resected specimens have been made in all cases. The postoperative thyroid status has been assessed clinically and also biochemically by serum thyroxine as iodine, T3 resin uptake, free thyroxine index and thyroid-stimulating hormone estimations. Serum calcium and phosphorus have also been measured and the necessary histological material reviewed. Postoperative hypothyroidism occurred in approximately 11 per cent of previously toxic and 6-5 per cent of non-toxic patients, becoming evident in most cases within a year of operation. The T3 resin uptake measurement following operation in this and previous series suggests that in many patients there is a compensation process which is maintained by increased secretion of thyroid-stimulating hormone. No evidence has been adduced that patients who show this compensation mechanism are, as some have suggested, in a state of ‘subclinical hypothyroidism’ or that they become overtly hypothyroid later. In this series hypothyroidism was more closely related to small remnant size than the presence of lymphadenoid change. A significantly higher proportion of patients with small thyroid remnants became hypothyroid in both toxic and non-toxic groups. Remnants of about 8-16 ml ‘cuboid’ volume (roughly 8-16 g by weight) have seemed reasonable for our patients.