Thyroxine suppressive therapy of benign solitary thyroid nodules: some problems

Assessing the effects of thyroid suppression on benign solitary thyroid nodules. A model for using quantitative research synthesis

Systematic review of the available information with a modified, largely quantitative method of research synthesis disclosed that an initial trial of thyroid hormone suppression therapy leads to clinically significant (> or = 50%) reduction of nodule size or arrest of nodule growth in a subset of patients with benign solitary thyroid nodules. In fact, in addition to objective improvements due to decreasing nodule size, L-T4 suppression therapy may benefit patients by reducing perinodular thyroid volume. Consequently, both pressure symptoms and cosmetic complaints may improve (9, 68). Additional studies for the assessment of the risks versus benefits of supraphysiologic doses of L-T4, the optimal level of thyroid suppression and the dose needed to achieve this magnitude of reduction, the optimal length of the initial trial, and the conditions for the continuation of L-T4 thyroid suppression therapy, as well as the identification of markers for patients most likely to respond to this therapy, are warranted. Finally, quantitative assessment of available evidence as described here may be applicable to the review of other controversial issues as well.

Thyroid hormone suppressive therapy of sporadic nontoxic goiter

Thyroid hormone has been used to reduce the size of sporadic nontoxic goiter since 1894. Noncontrolled clinical studies suggest that about two thirds of goiters respond to therapy, and a recent randomized clinical trial confirms the efficacy of suppressive therapy for sporadic nontoxic goiter. Efficacy is at least partly correlated with suppression of pituitary TSH production, response is usually evident by 3 months, relapse occurs when therapy is withdrawn, and nodular goiters may be less responsive than diffuse goiters. Some, but not all, series suggest that postoperative use of thyroid hormone suppressive therapy prevents recurrence of benign goiter. Three recent randomized trials suggest that thyroid hormone administered for 6 months to 3 years does not reduce the size of solitary thyroid nodules. About one third of nodules regressed in both treatment and placebo groups. Long-term studies are needed to define the effects of thyroid hormone suppressive therapy on the growth of goitrous lesions based on their underlying pathophysiology.