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    Can high dosage of thyroid replacement hormones cause atrial fibrillation?

Posted on Tue, 8 Aug 2017 in Thyroid Problem and Hormonal Problems
Question: My endocrinologist overdosed me on too high a dose of T3 & T4 which after about 6 months sent me into Afib.
On advice, I stropped the thyroid medication, not understanding next in line would be bradychardia (sp?). While "settling down" and undergoing thyroid medication withdrawal my heart beat fluctuated between 214 beats and 41 beats pm. The Afib resolved, but the bradychardia worsened so I am being titrated back up on thyroid, only to find that the Afib is returning. Question: Shouldn't I also be tested for iron, anemia, vit. B., adrenal sufficiency and pituitary as part of a global response diagnosis? Thank you for any input- I see my new Endo on August 3rd. So I am hopeful but worried.
Answered by Dr. Elona Xhardo 56 minutes later
Brief Answer:
Yes, you should.

Detailed Answer:
I have gone through your question and understood your concern.

It is true that the overdoses of thyroid hormone replacement therapy can accelerate the cardiac rhythms and produce Atrial fibrillation.

The opposite, the absence of thyroid hormone can result in bradycardia.

This problem can be resolved with the very gradual titration of the doses of the hormone replacement therapy.I'm sure that your doctor will guide you how to titrate the doses of your medication.

About your question, I can say that anemia(both from iron or from B12 deficiency) do not produce Afib or bradycardia, so these tests are not necessary in your case.

The adrenal deficiency can be related to bradycardia but in this case, you should have even other important symptoms like Extreme fatigue.

Weight loss and decreased appetite, Darkening of your skin, Low blood pressure, Low blood sugar.

You did not mention any of these symptoms, so even this diagnosis can be excluded and the tests for this diagnosis, are not necessary in your case.

The same logic is even for the pituitary deficiency. So, in my opinion, you don't need another test apart from thyroid test(TSH in your case)

Hope this is helpful.
Best regards.

Above answer was peer-reviewed by : Dr. Arnab Banerjee
Answered by
Dr. Elona Xhardo


Practicing since :2008

Answered : 814 Questions


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