Thyroid Research Thyroid Research Archive Hypothyroidism

Lack of benefit of thyroxine in patients with mild subclinical hypothyroidism

(July 2002)

The background of the study. Subclinical hypothyroidism (high serum thyrotropin [TSH], normal serum thyroxine [T4]) is common. Whether patients with the disorder have symptoms and whether the symptoms improve with T4 therapy are controversial. In this study T4 therapy was evaluated in carefully selected patients with subclinical hypothyroidism.

How the study was done. The study subjects were 45 women (mean age, 49 years) who had symptoms suggestive of hypothyroidism and who had serum TSH concentrations between 5 and 10 mU/L and normal serum free T4 concentrations. The women were randomly assigned to receive 0.05 mg T4 or placebo daily for six months. Health questionnaires were administered, and symptoms of hypothyroidism and thyroid function and serum lipids were measured before and after T4 therapy for three and six months.

The results of the study. The base-line characteristics, including all questionnaire scores, the hypothyroid symptom score, and biochemical values, of the women in the two groups were similar. Twenty women in the T4 therapy group and 15 women in the placebo group completed the study.

At six months, the mean serum TSH concentration decreased by 4.6 mU/L in the T4 therapy group and by 1.7 mU/L in the placebo group. The health questionnaire scores did not change significantly in either group, nor did the proportions of women in whom the scores improved, did not change, or worsened. The hypothyroid symptom score decreased to a similar extent in both groups. There were no changes in body-mass index or serum lipid concentrations in either group.

The conclusions of the study. T4 therapy for six months has no benefit in women with mild subclinical hypothyroidism.

The original article. Kong WM, Sheikh MH, Lumb PJ, Freedman DB, Crook M, Doré CJ, Finer N. A 6-month randomized trial of thyroxine treatment in women with mild subclinical hypothyroidism. Am J Med 2002;112:348-54.