Do we give too many people thyroxine?
No question, if your thyroid is really underactive you need thyroid hormone replacement. However an article just published online in the Journal of the American Medical Association (JAMA) Internal Medicine suggests that too many people, particularly older people, are given thyroid hormone.
The article cites the case of a 72-year-old man who was started on thyroxine, and soon after attended ED with palpitations, shortness of breath, and chest pain. He had a common heart rhythm disturbance called atrial fibrillation.
Here's the problem in a nutshell: Underactive thyroid is common, affecting around 3% of the population. Hypothyroidism should be treated. However, many more people have what is called "subclinical hypothyroidism". Here, thyroid hormones are in the normal range, but the hormone TSH is increased. Thyroid symptoms do not correlate real well with thyroid hormone measurements, particularly when the abnormality is mild. Increased TSH (a hormone produced in the pituitary) is a sign that the body is trying to drive the thyroid gland to produce more thyroid hormones.
Subclinical hypothyroidism affects between 4 and 12% of the population. This may be up to 20 million people in the United States and up to one billion people worldwide. Thyroxine is the most prescribed medication in the United States.
Are we giving too many people thyroid replacement? The JAMA article reminds us that thyroid hormone replacement has risks, as well as potential benefits. However, the symptoms from an underactive thyroid affect people differently. Some people get symptoms when the thyroid under activity is only mild or subclinical.
