The Value of Early Triiodothyronine Suppression Test in the Prognosis of Thyrotoxicosis

Abstract

Triiodothyronine suppression tests with estimation of ¹³¹I uptake 20 min after i.v. injection were performed at 6-monthly intervals on 69 thyrotoxic patients treated with Carbimazol and L-triiodothyronine for 18 months. 29 patients relapsed while 40 remained euthyroid. The prognostical value of the suppression test was evaluated statistically. Uptakes under 8 per cent after 6 months' treatment suggest the patient will not relapse (prognostic sensitivity 0.8). Uptakes over 8 per cent do not select patients who relapse (prognostic specificity 0.4–0.5).

Key Words:

• Hyperthyroidism
• thyroid suppression
• triiodothyronine suppression test