More Research: New England Journal

From ThyroWorld Volume 3, No 1, Spring 2000.

A new study on hypothyroidism was reported in 1999 in the New England Journal of Medicine. The Research project dealt with the best treatment for hypothyroidism, a topic on which the medical jury is still "out".

The best treatment for hypothyroidism?

In their study, Dr. Bunevicus and colleagues raised some important issues about thyroid hormone therapy. In their study, 33 patients with severe hypothyroidism were treated alternatively with either pure thyroxine (T4) or a lower dose of T4 plus triiotathyronine (T3), a more rapidly acting thyroid hormone. Their suggestion is not new, for we have long known that both hormones exist in the thyroid gland and in the circulation of the blood. There are even preparations on the market today that were developed to try to match the balance of T3 and T4 in the blood. In the past, investigators were not able to demonstrate significant differences in the clinical effects of combined hormone treatment as compared with pure thyroxine treatment. Therefore, almost all physicians prescribe pure thyroxine (T4). We also know that thyroxine can be converted by the body to T3 and assume that this occurs as needed. Physicians also are concerned that a tablet of T3 causes higher than normal blood levels of this hormone, posing a risk for dangerous cardiac arythmias and heart attacks, especially for elderly individuals or anyone with heart disease. Thus most thyroid patients are treated with thyroxine alone and generally feel well.

There are some thyroid patients, however, who do not feel well on pure thyroxine treatment. For some, another problem such as hay fever, heart disease, or depression may be the problem. For others, the information obtained by Dr. Bunevicus and his colleagues suggests that some may feel better by reducing T4 and combining it with small amounts of T3.

Clearly more research is needed in the field and doctors still need to be cautious about using the rapidly acting T3 in individuals who are elderly or have heart problems.