Rose5: I was diagnosed with Hashimoto thyroiditis by an endocrine physician. I am on Armour® Thyroid 90 mg by a wellness doctor. The endocrine physician who diagnosed me felt I should not be on any medication, but was OK with low-dose Armour® Thyroid 30! Now he is worried about atrial fibrillation. My blood work has been monitored. Does Armour® Thyroid cause atrial fibrillation over the long term? What other recommendations do you have for this diagnosis?
Suman_Jana,_MD: Atrial fibrillation is from too much thyroid hormone (T4 and T3) leading to low TSH. So, if your TSH is not low, the risk of atrial fibrillation is not high. Compared to T4, T3 has a high potency to suppress TSH. In Armour® Thyroid, there is a relatively higher percentage of T3 than we really need. Armour® Thyroid is made from thyroid gland extract from pig and cow. Now, animals need more T3 than humans. T3 helps them with more thermogenesis (body heat production). Since animals don’t wear clothes, they need to preserve body heat by generating more heat production.
Jack_in_Florida: Does overcompensating on thyroid medication contribute to potential atrial fibrillation episodes? Can you comment also on target levels for T3 uptake, T3, free T3, TSH, T4 and free T4 for those on thyroid replacement therapy? (I have no thyroid gland.)
Suman_Jana,_MD: Atrial fibrillation is from too much of thyroid hormone (T4 and T3) leading to low TSH. So, if your TSH is not low, the risk of atrial fibrillation is not high. Compared to T4, T3 has a high potency to suppress TSH. TSH levels should be above the lower limit of normal.