Over the years, I’ve seen many patients develop atrial fibrillation (AFib) from having an overactive thyroid gland or from taking too much thyroid hormone.

The thyroid gland, which sits in the neck, is responsible for producing thyroid hormone that controls the metabolic rate of every cell in the body. Too much or too little of this hormone can lead to health problems.

Inadequate production of thyroid hormone is called hypothyroidism. When too much thyroid hormone is produced, it is known as hyperthyroidism.

Hyperthyroidism can be caused either by the overproduction from the thyroid gland or by ingesting too much of the hormone.

However it is caused, too much thyroid hormone can lead to a rapid heart rate, sweating, nervousness, and a jittery feeling.

When I see someone who exhibits signs of hyperthyroidism, I order thyroid function blood tests to identify the problem.

A low level of thyroid stimulating hormone (TSH) can indicate that there is too much thyroid hormone in the body. This can be confirmed by testing the active thyroid metabolites — T3 and T4.

I pay close attention to these numbers because, as noted, too much thyroid hormone can cause problems — particularly in the elderly.

People over the age of 65 are very sensitive to excess thyroid hormone. Doctors have to be very cautious about prescribing thyroid hormone to older people. When I do, I start with a low dose and raise it much more slowly than I do with younger people.

If you are suffering atrial fibrillation, get a proper workup of your thyroid gland to ensure that you do not have hyperthyroidism.

Often, correcting hyperthyroidism can make atrial fibrillation go away quickly.