Medical Q&As

Thyroxine - weight gain?

I have just been diagnosed with an under active thyroid and was prescribed thyroxine. I had always understood that people with this problem were overweight. I would like to know if it is taking thyroxine medication that produces the weight?

An under active thyroid gland means that the gland is not producing sufficient amounts of thyroxine, which is also referred to as thyroid hormone. The thyroxine tablet is a synthetic form of thyroid hormone that is taken orally in order to compensate for this deficiency. Thyroxine directly affects the body’s basal metabolic rate, which is the technical phrase for the rate at which the body burns off energy. A person with a low rate tends to gain weight because the body is not burning off energy efficiently. Therefore a person with an under active thyroid gland will tend to gain weight. Correcting the deficiency through the administration of thyroxine speeds up the metabolic rate and corrects the tendency to gain weight.