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.