Thyroid stimulating hormone suppressive therapy in solitary thyroid nodule

Abstract EN

Objectives : To study the effect of thyroid stimulating hormone suppressive therapy with Levothyroxine on the size of a thyroid nodule in patients with a single benign thyroid nodule.

Methods : This is a prospective randdmized, open label controlled study conducted over a period of oneyear (February 1999 to February 2000).

Eighty six volunteers with a palpable thyroid nodule, single by high resolution sonography, biochemically euthyroid, cold on Technetium 99 scintigraphy, and benign on cytological examination by fine needle aspiration biopsy, were included in the study.

Forty- three of them were randomly allocated to treatment with Levothyroxine in a thyroid stimulating hormone suppressive dose (Thyroid stimulating hormone < 0.5 / iU / mL) for six months.

The rest of the volunteers received no treatment.

Patients were followed up, clinically by thyroid function tests, and ultrasound imaging at 0, 3, 6 and 12 months.

Changes in the nodule size were recorded Results : There were thirty women and thirteen men in the treatment group.

Female : Male ratio was 2.3 : 1.

In the control group there were thirty two women and eleven men.

Female : Male ratio was 2.9:1.

The mean age in the treatment group was 28.4+1.2 years (age + SD) with an age range of 15- 58 years.

In the control group the mean age was 29.2+ 1.4 years (age + SD) with an age range of 16- 62 years.

The mean dose of levothyroxine necessary for significant suppression was 0.2lmg (Thyroid stimulating hormone <0.5 nU / mL).

No significant changes in the thyroid nodule diameter before and after six months of suppressive therapy in the treatment group (mean + SD) 2.8±1.1 cm vs 2.7± 1.2 cm (p-value 0.31) was noticed.

Similar results were obtained in the control group: 2.7 ± 1.2 cm vs 2.6 +1.1 cm (p-value 0.31).

Significant reduction of the nodule size (< 50 %) was achieved in eight individuals (18.6 %) in the treatment group.

Six individuals (13.9 %) in the control group showed significant reduction of the nodule size, therefore, the difference between the treatment and the control group was not statistically significant, (p-vulue 0.34).

Conclusion: Thyroid stimulating hormone suppressive therapy with levothyroxine failed to achieve significant reduction of the nodule size in individuals with solitary benign euthyroid nodule when compared with the no treatment group.

Therefore, solitary benign euthyroid nodules are better followed up without treatment.

Nodules that increase in size should have a repeat fine needle aspiration biopsy.