Suppressive therapy with levothyroxine for euthyroid diffuse and nodular goiter.

In this study, 35 patients with euthyroid diffuse goiter and 35 patients with euthyroid nodular goiter were treated with Levothyroxine (L-T4) for six months. The aim was to evaluate the efficacy of treatment on thyroid and nodule volumes and to evaluate the correlation between volume changes and thyroglobulin levels. Serum thyroid hormones, TSH, thyroglobulin, thyroid and nodule volumes were measured at the initial visit and after 6 months. Radioactive iodine uptakes of the thyroid gland were evaluated before treatment. The mean decrease of thyroid volume at six months was about 20% (20.4 +/- 8.8 ml vs. 16 +/- 7.9 ml, P<0.001) in patients with diffuse goiter. All patients with diffuse goiter showed some decrement in their goiter sizes. Thyroid nodules, in response to thyroid hormone treatment, showed a variable behavior. A reduction of 50% or more in volume was detected in 31% (11/35) of the patients. 54% of the patients (19/35) showed a 10-49% decrease in nodule volume. Five of the patients were found to be insensitive to the therapy. Their nodule volumes either increased or did not change during therapy. Free T4 and free T3 levels increased and TSH levels decreased with L-T4 treatment in all patient groups. Patients with higher TSH levels (within normal limits) showed more volume reduction in the diffuse goiter group. No uniform correlation was found between volume changes and thyroglobulin levels in either of the patient groups. In conclusion, suppressive thyroxine treatment is effective in reducing the size of the goiter, and nodules and thyroglobulin levels cannot be taken as an indicator of the efficacy of L-T4 therapy.