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Levothyroxine and Potassium Iodide Are Both Effective in Treating Benign Solitary Solid Cold Nodules of the Thyroid
- Giacomo L. La Rosa, MD;
- Lorenzo Lupo, MD;
- Dario Giuffrida, MD;
- Damiano Gullo, MD;
- Riccardo Vigneri, MD; and
- Antonino Belfiore, MD
- From the University of Catania, Catania, Italy. Requests for Reprints: Giacomo L. La Rosa, MD, Cattedra di Endocrinologia, Ospedale Garibaldi, Piazza S. Maria di Gesu, 95123 Catania, Italy. Acknowledgments: The authors thank the Cyanamid Italia SpA for providing the potassium iodide tablets; Dr. A. Nastri for his help in the study design; and Drs. C. Regalbuto, L. Sava, V. Freni, M.G. Santonocito, and G. Briguglia for their help in the recruitment and follow-up of patients.
Abstract
Objective: To determine the effectiveness of levothyroxine and potassium iodide in treating patients with benign solitary cold thyroid nodules.
Design: Randomized controlled study.
Setting: Outpatient clinic at a university hospital.
Patients: 80 patients with solitary solid cold thyroid nodules found to be benign at cytologic examination were randomly assigned to no treatment, suppressive levothyroxine (thyroid-stimulating hormone level, <0.3 mU/L), or low-dose potassium iodide (2 mg every 2 weeks). Seventy patients completed the 1-year study. After 1 year, patients receiving treatment discontinued drug therapy and were re-evaluated 4 months later; patients receiving no treatment were given levothyroxine and were followed for a second year.
Measurements: Nodule volume was measured by ultrasonography at 4-month intervals by an observer masked to treatment assignment.
Results: Mean nodule volume decreased by 40% of the basal volume in the 23 patients receiving levothyroxine (P < 0.001) and by 23% of the basal volume in the 25 patients receiving potassium iodide (P = 0.053). Volume slightly increased in the 22 untreated patients (P = 0.085). A clinically relevant reduction in nodule volume (≥ 50%) was observed in 9 of 23 patients treated with levothyroxine, in 5 of 25 patients treated with potassium iodide, and in none of 22 untreated patients (P = 0.004). Only nodules with a volume of 10 mL or less were reduced; nodules with volumes of 5 mL or less shrank most frequently. Nodule volume did not relevantly increase in treated patients but did increase in 3 of the 22 untreated patients. Drug withdrawal resulted in an increased mean nodule volume (P = 0.004) after 4 months.
Conclusions: Levothyroxine and, to a lesser extent, potassium iodide are effective in arresting the growth or in reducing the volume of benign solitary solid cold thyroid nodules, especially small ones; discontinuation of therapy may result in resumed nodule growth.
- Copyright ©2004 by the American College of Physicians
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