Thyroid Research Thyroid Research Archive Hypothyroidism

Thyroxine therapy does not improve well-being or cognitive function in patients with symptoms of hypothyroidism but normal thyroid function

(March 2002)

The background of the study. Fatigue, lethargy, weight gain, cold intolerance, and dry skin or hair are common not only in people with hypothyroidism, but also in those with normal thyroid function. In general, these symptoms improve during treatment with thyroxine (T4) in people with hypothyroidism, but whether treatment with T4 benefits those with normal thyroid function is not known.

How the study was done. Two groups were studied. One consisted of 25 patients who had at least three of six symptoms that are common in patients with hypothyroidism for at least 6 months: lethargy, tiredness, weight gain or inability to lose weight, cold intolerance, hair loss, and dry hair or skin. The other group consisted of 19 normal subjects who had no symptoms. All had normal thyroid function. The study subjects were given 0.1 mg of T4 or placebo daily for 12 weeks, in random order. Psychological and physical well-being and cognitive function were measured at the end of each treatment period.

The results of the study. At base line, the patient group had higher levels of anxiety and depression, and scored lower on the physical well-being and general health tests and the tests of cognitive function.

In the patient group, there were small improvements in anxiety and depression, physical well-being, and general health during both the T4 treatment and the placebo periods, with no difference between the two periods, but there were no changes in cognitive functioning during either period. There were also no changes in any of the scores or tests during either period in the group of normal subjects.

The conclusions of the study. T4 treatment does not improve psychological or physical well-being or cognitive function in patients who have some symptoms of hypothyroidism but normal thyroid function.

The original article. Pollock MA, Sturrock A, Marshall K, Davidson KM, Kelly CJ, McMahon AD, McLaren EH. Thyroxine treatment in patients with symptoms of hypothyroidism but thyroid function tests within the reference range: randomised double blind placebo controlled crossover trial. BMJ 2001;323:891-5.