Purpose: To review evidence about thyroxine suppressive therapy in patients with thyroid nodules, including the clinical importance and natural history of nodules and the effects and potential side effects of thyroxine therapy.
Data Sources: English-language articles published from 1986 to December 1996 were identified through searches of the MEDLINE database, selected bibliographies, and personal files.
Data Extraction: Randomized, controlled trials and non-randomized trials of thyroxine suppressive therapy for solitary and predominantly solid thyroid nodules were reviewed. In most studies, nodule cytology was evaluated by fine-needle aspiration biopsy. Therapy was considered suppressive if suppression was documented by thyroid-stimulating hormone-releasing hormone tests or sensitive thyroid-stimulating hormone assays. Response was defined as a decrease of 50% or more in nodule size or volume; most recent studies measured nodule size by ultrasonography.
Data Synthesis: The evidence suggests that thyroxine suppressive therapy fails to shrink most nodules: Only 10% to 20% of nodules responded to this treatment. Fineneedle aspiration biopsy is more reliable in distinguishing benign from malignant nodules. Recent studies suggest that spontaneous decrease in size with complete disappearance of thyroid nodules is not uncommon. No data show that thyroxine therapy arrests further growth in most existing nodules or prevents the emergence of new nodules. Postoperative thyroxine therapy does not seem to prevent recurrence of thyroid nodules except in patients with a history of radiation therapy. Potential adverse effects of long-term suppressive therapy include osteoporosis and heart disease.
Conclusions: Patients with cytologically benign nodules are best followed without thyroxine treatment. Most benign nodules remain stable in size and remain benign when monitored for a long time. For nodules that increase in size, biopsy should be done again or surgery should be performed.