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Was Hypothyroid, Now Hyperthyroid?

TSH thyroid IVF

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#1 angelgirl

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Posted 22 December 2011 - 11:15 AM

Hello Dr. Fiona,

I have been reading your advice about subclinical hypothyroism and infertility with great interest. I have a family history of hypothyroidism and so have had my TSH, T3 and T4 levels tested regularly for many years. My TSH has always bobbed between 3 and 4.5 - which my doctors all consider normal. However, I have also read that others believe a TSH between 1 and 2 is best if trying to get and stay pregnant.

I am about to begin a 2nd round of IVF and raised this issue with my doctor again. Happily, she agreed to treat me with Synthroid - she noted that some recent new studies indicate that TSH levels should be below 2.5 for patients undergoing IVF. I had my TSH measured in early November and it was 3, so I started Synthroid (100 mg/day) on Nov. 11th. Just over 4 weeks later, I had another blood test and my TSH level had plunged to 0.49.

While I'm happy that my levels have dropped, I wonder if they have dropped too much? Is a TSH of below 1 considered too low for fertility? Should I be concerned, now that I have gone from a high-normal TSH to a low-normal one? My doctor thinks my current low levels are fine, but I would like another opinion. Thank you in advance!

#2 DrFionaMcCulloch

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Posted 27 December 2011 - 10:14 AM

Hi Angelgirl

This level should be ok for IVF as long as you are not hyperthyroid (the TSH is a screening tool and it being at the low end of the range can be common when supplementing thyroid hormone, without any problems at all). To be extra sure, you can check your antithyroid antibodies, free T3 and free T4 and see if they are within the range. Also, if you are experiencing any symptoms of hyperthyroidism such as palpitations, jitteriness, anxiety, weight loss or sweating then you should consider lowering the dose by a small amount.

Thanks so much for your question!

Dr Fiona
Dr. Fiona McCulloch, BSc., ND : Naturopathic Doctor, Integrative Women's Health & Fertility
White Lotus Integrative Medicine
Greenfield Ave, Suite 201
North York, Ontario, M2N 3CBCanada
phone (416) 730-8218


#3 angelgirl

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Posted 28 December 2011 - 03:51 PM

Thank you so much for responding, Dr. Fiona. My free T3 and T4 levels are in a normal range, and I haven't experienced any of the hyperthyroid symptoms you described. So, I'm feeling reassured that my levels are OK.

Thanks again!

Also tagged with one or more of these keywords: TSH, thyroid, IVF