Effectiveness of Thyroid Hormone Suppressive Therapy in Benign Solitary Thyroid Nodules: A Meta-Analysis

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Abstract
The effectiveness of thyroid hormone suppressive therapy in reducing the volume of benign thyroid nodules is controversial. It is important to clarify this therapeutic effect of thyroid hormone, because its prolonged use needs to be carefully weighed against its potential deleterious effects in the skeletal and cardiovascular systems. To evaluate the best available evidence, we conducted a systematic review and meta-analysis of the randomized controlled trials that fulfill the following inclusion criteria: single thyroid nodules proven benign by fine needle aspiration, treatment, and follow-up of at least 6 months; documented suppression of TSH; measurement of thyroid nodule volume by ultrasound; and response to therapy defined as more than 50% volume reduction from baseline. Six randomized clinical trials published between 1987 and 1999, with 346 patients, were included in the meta-analysis. Ninety percent of the participants were female. Using a random effects model, the overall effect size showed a relative risk of 1.9 (95% confidence interval, 0.95–3.81) favoring a treatment effect. A sensitivity analysis showed significant changes in the results. Suppressive thyroid hormone therapy for longer than 6 months is associated with a trend toward a reduction of more than 50% in volume of benign thyroid nodules, without achieving statistical significance. The results are highly sensitive to changes in the statistical analysis, especially if the method used ignores heterogeneity among the effect sizes. More studies are needed before this therapy can be widely recommended.