On the usefulness of levothyroxine suppressive therapy in the medical treatment of benign solitary, solid or predominantly solid, thyroid nodules

Abstract

Abstract. The efficacy of levothyroxine suppressive therapy in the treatment of benign solitary thyroid nodules is controversial. In order to investigate this issue further we studied 122 patients with a solitary, solid or predominantly solid, thyroid nodule. The benign (colloid) nature of all nodules was proved by fine-needle aspiration biopsy. At the pertechnetate-99m thyroid scanning 91% of the nodules were "cold" and 9% "warm". All the patients received suppressive oral doses of levothyroxine (0.1 to 0.2 mg/day). Fifty-three patients were treated with levothyroxine for 6 months, 31 for 9 months and 38 for 12 months. The size of each nodule before and after treatment was evaluated by high-resolution ultrasonography. The actual suppression of TSH secretion was monitored at 3-month intervals using an ultrasensitive immunometric assay. At the end of levothyroxine treatment, patients were classified as responders (decrease in nodule volume ≥50%, 68/122 = 55.7%; mean percent change in nodule volume = −77.1 ± 15.7%), partially responders (decrease in nodule volume <50%, 24/122 = 19.7%; mean percent change in nodule volume = −27.5±10.1%), and nonresponders, when either no change in nodule volume (16/122 = 13.1%) or an increase in nodule volume (14/122 = 11.5%) was observed. In each group serum free T4 rose significantly in response to levothyroxine therapy, whereas serum free T3 remained unchanged. TSH levels were undetectable in all patients. Both the proportion of responders, partially responders and nonresponders, and the mean percent decrease in nodule volume in the responder group were not significantly different in patients treated with levothyroxine for 6, 9 or 12 months, respectively. Therefore, it appears that levothyroxine therapy is effective within 6 months in reducing the size of colloid solitary, solid or predominantly solid, thyroid nodules or in preventing their further growth in about 90% of our patients.