CENTRAL  SOUTH  DAKOTA  MEDICAL NEWS
 THE CLINICAL VIEW
By: Phillip E. Hoffsten, M.D.
11/16/2000

 Low Thyroid Function

The thyroid gland is located over the front and sides of the trachea in the neck. It secretes a hormone that functions like the accelerator in your car; a little more thyroid hormone speeds up the body's metabolism and a little less cuts down the rate of the body's metabolism. Thinking of this in another way, thyroid hormone leads to the body burning more calories and having more energy.  The other side of the coin is that not enough thyroid hormone leads to lower calorie expenditure and decreased energy. This is associated with fatigue, overweight and a lethargic slow feeling. In the extreme situation, the skin becomes coarse, the voice becomes deeper and is described as almost frog-like. Heart failure is common.

Hypothyroidism is the medical term used to describe not enough thyroid hormone. The prefix hypo- means not enough or low levels whenever this is applied as a prefix to a medical word. Thus, hypothyroidism means not enough thyroid hormone.

In the distant past before the importance of this hormone was discovered, our mental institutions had a significant number of inmates who had what is called myxedema madness. Myxedema is another medical term to describe hypothyroidism but it describes an extreme state of hypothyroidism. In the extreme state, the individual does develop significant mental symptoms including loss of memory, loss of ability to perform activities of daily living and delusions.

Next to diabetes, hypothyroidism is probably the most common hormone deficiency in medicine. There are many illnesses of the thyroid gland that decrease its function. Rarely, the person has a tumor in the pituitary gland in the brain that decreases the amount of thyroid stimulating hormone the brain produces. This hormone is regulated by a set of cells in the brain that measures how much thyroid hormone is in the blood then the pituitary gland releases thyroid ­stimulating hormone (TSH) to tell the thyroid to make more or less thyroid hormone as needed. If a person develops a tumor or abnormality of the pituitary gland, hypothyroidism is relatively common.

By far, the more common cause of hypothyroidism is a primary abnormality of the thyroid gland itself. In that case, the thyroid-stimulating hormone (TSH) is secreted in markedly increased amounts by the pituitary gland to tell the thyroid "please make more thyroid hormone". Unfortunately, the thyroid gland does not listen and the hypothyroid problem persists. This can then be treated by replacing an amount of thyroid hormone that a person needs through a pill. Very conveniently, the amount and size of the pill needed can be regulated by measuring the blood TSH level, a laboratory blood test that is available in all our clinics. The thyroid replacement hormone pill now comes in many different sizes.

A common misconception is that a person with a "low metabolism", being somewhat overweight, and having low energy levels must be hypothyroid. A relatively common inquiry by patients involves their belief that they must be hypothyroid because they just do not have any energy or they are tired all the time. Were the problem so easy it would be nice but hypothyroidism is a relatively unusual cause of a person being overweight or being tired. Fortunately, with the ability to measure the blood TSH level, a specific answer can be obtained at the clinic as to whether or not a person has a low thyroid level.

As a final consideration, it must be noted that over treating low thyroid levels is not without its own problems. Too much thyroid hormone contributes to osteoporosis. Thus, it is important to monitor thyroid replacement treatment and be sure that the person is not getting too much thyroid hormone replacement. The health care professionals at your local clinics are aware of these types of problems and can be of help in diagnosing hypothyroidism and adjusting medications appropriately.