Rapid reversal of subclinical hyperthyroidism in patients with large multinodular goitres after thyroidectomy.

A patient is said to have subclinical hyperthyroidism if he has a depressed thyroid stimulating hormone (TSH) level but is clinically euthyroid and has a normal thyroxine (T4) and triiodothyronine (T3) level. The aetiology of this condition is unknown, its progression is uncertain and the value of treatment is doubtful. These 2 cases show a rapid reversal of TSH suppression within a week after thyroidectomy. This suggest an unidentified potent but innocuous suppressor of TSH is produced by some large nodular goitres. Patients with multinodular goitres with subclinical hyperthyroidism can have their anxiety allayed with assurance that their condition is benign and that their TSH suppression is due to the presence of an innocuous substance which is protective in nature. This substance, when isolated, will find a useful place in the prevention and treatment of papillary carcinoma of the thyroid because of its potent effect on the pituitary-thyroid axis without causing any peripheral effects.