The Wellness Q&A with Elaine Moore

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methimazole dosing advice
Last Post 21 Feb 2021 07:45 PM by Elaine Moore. 1 Replies.
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renoUser is Offline New Member New Member Posts:
19 Feb 2021 03:47 PM
    Hello Elaine,
    Writing once again as I've had a setback in my thyroid hormone levels, and could use some dosing advice for the next few months. If you will recall, I came out of remission 2 months ago after 2 years of being euthyroid. I have not been on methimazole during the remission. The following are my labs.

    Dec 23, 2020

    FT3. 7.2. (2.2-4.0)
    FT4 1.89 (0.76-1.46)
    TSH < 0.01

    I took 10 mg methimazole for 2 weeks and 5 mg for 2 weeks

    Jan 20, 2021

    FT3 4.5
    FT4 1.0
    TSH. < 0.01

    With your help I went to 3.75 mg for 1 week and then 2.5 mg for 3 weeks
    I voiced that I wanted to be conservative so as not to dip into hypo

    Feb 18, 2021

    FT3 7.8
    FT4 1.98
    TSH. < 0.01

    I guess I was a bit too conservative with the meds and am back where I started unfortunately. I also started back on 60 mg

    Would you mind suggesting where I go from here? My primary tends to suggest too high a methimazole dose
    as she does consider TSH, wihich I know is not correct. I am having this conversation with her soon.

    I'm still looking for a soft landing. Back to 10 mg for a month?

    Your advice is much appreciated!
    Elaine MooreUser is Offline Veteran Member Veteran Member Posts:3567
    21 Feb 2021 07:45 PM
    Hi Reno,
    FT3 does take longer to fall but with it persisting you would be a good candidate for block and replace. With a dose of 5 mg your FT4 didn’t fall too low but 2.5 mg caused too high of a rise.
    You’d do well on 3.75 -5mg although FT3 would take longer to fall. Propranolol will help FT3 fall although a 60 mg dose may cause your heart rate to fall too low.
    A 10 mg MMI dose would lower FT3 sooner but you’d need around 37.5 mcg of levothyroxine in a block and replace protocol to make sure you have enough FT4. If FT4 falls too low forbyour needs even if it falls within the reference range it encourages thyroid antibody production and prevents remission.
    It’s always a good idea in T3 thyrotoxicosis to have an FT3 by dialysis blood test to make sure FT3 isn’t falsely elevated. This test is the most likely one to be falsely elevated.
    Either block and replace or the lower MMI dose would work and it’s good you’re making sure FT4 doesn’t fall too low. Best, elaine
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