Cardiology

High-normal levels of thyroid hormone risky arrhythmia

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Thyroid is some “doctors” favorite.

Thyroid is becoming the popular target that some kinds of doctors’ favorite to treat. Its physiology is easy to understand so that these practitioners feel more confident in dealing with it. Even the levels of thyroid hormone is within the normal limit, they will give some thyroxine substitute to treat the symptoms that might be attributed to thyroid. Patients sometimes do feel better with more thyroid hormones in their body before they get the hyperthyroid symptoms. This is the concept of subclinical hypothyroidism that is the favorite topic of some practitioners.

Subclinical hypothyroidism means that the lab values of thyroid hormone are normal but practitioners think the patients’ thyroid function is still low and is the cause of the patient’s symptoms. The abnormally increased levels of thyroid hormone causes atrial fibrillation, one kind of arrhythmia that can lead to stroke. Recent data shows that even the thyroid hormone is within normal limit, the high-normal levels of free thyroxine, which is one type of thyroid hormone, is related to higher risk of atrial fibrillation and higher risk of sudden death. This is a serious warning for the potential over-treatment of subclinical hypothyroidism.

What to do.

Consult with your cardiologist and endocrinologist before you jump into these treatments to make yourself feel better. As a matter of fact,  decreased thyroid function with normal-low level of thyroid hormone may represent a protective condition in healthy aging and is a good sign for longevity. This is consistent with the eastern philosophy, which is to conserve the energy for future use.

References:

http://circ.ahajournals.org/content/early/2017/10/18/CIRCULATIONAHA.117.028753

http://circ.ahajournals.org/content/134/10/713.long

https://academic.oup.com/jcem/article-lookup/doi/10.1210/jc.2010-0875

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