Diabetes

Poss synthroid overdose

11/15/2005 05:53PM

Question:

I recently had a gastric bypass aprox 4 months ago. I had graves disease about 6 years ago which resulted in RAI, since this I have been on 175 of synthroid. I have lost 44 lbs in less than 4 months and in the last couple of weeks have developed some chest pain, lots of shortness of breath, abd pain, change in menses(increase), rapid heart beat, nervousness, I decreased my dose to half a pill a day then to none at all with my PcP nurse`s suggestion until I could get in to see the doctor. I believe this is all related to the rapid weight loss and not realizing the need sooner to reduce my synthroid dose. My last tsh level was extremly low, almost as low as it was when my graves disease was diagnosed..my question is; how long will it take the synthroid to reduce to a more normal level and these symptoms to decrease, the shortness of breath bothers me the most which causes anxiety, which causes more problems. Is there any medication that could counter act the synthroid sooner than waiting for it to exit my system? thanks in advance for any information you have.

Answer:

Gastric bypass has the potential to alter absorption of drugs. Substantial weight loss has the potential to reduce requirements for thyroid hormone replacement in people with hypothyroidism (an underactive thyroid). Hypothyroidism is a common consequence of treating such overactive thyroid conditions as Graves Disease with RAI (radioactive iodine treatment). If you are experiencing chest pain with rapid heart beat and shortness of breath, I would not delay in making arrangements to be seen by the doctor. You didn't mention your age but it is a concern whether the chest pain is a manifestation of coronary heart disease, regardless of whether a change in thyroid hormone blood levels brought it on. I don't have sufficient information to evaluate what you describe as chest pain. There are some circumstances in which I would advise a person with chest pain to go to an emergency room and others where I would not. How well I know the person is a major ingredient in how I make that judgement and clearly I have no further information about you.

In general, we allow 4-6 weeks when we make an adjustment in dose of L-thyroxine, a medication that is sold under several different brand names, Synthroid being one of them, before we expect the hormone level to stabilize. My guess is that symptoms as you describe should clear within probably 2-3 weeks of stopping the L-thyroxine in a person with no thyroid function of their own IF the L-thyroxine is responsible for the symptoms. A recurrence of the overactive thyroid condition is possible but less likely than an alteration in dose requirement.

A drug in the class known as beta blockers is sometimes used to reduce the effects of hyperthyroidism on the heart and is also used in some people with coronary heart disease to slow the heart and improve the time for blood delivery to the heart muscle. That would be one of the several possibilities to consider in this situation.

For more information:

Go to the Diabetes health topic, where you can:

Read articles on this topic
Browse the previously asked questions
Ask your own question.

Response by:

Robert M. Cohen, MD
Associate Professor
Division of Endocrinology and Metabolism
Department of Internal Medicine
College of Medicine
University of Cincinnati