Help please! Methimazole Dose to take? - Latest... - Thyroid UK

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Help please! Methimazole Dose to take? - Latest labs show almost hypothryoid with T3


Hi Everyone,

I posted a short while ago I was concerned I was being over-medicated. Latest results show I'm just right over the bottom range on my T3.

Can anyone tell me how much to taper down to?

My endo refuses to taper me down more, and after a really bad visit - I'm now looking for another one. I have an appt with my GP next week to help me. I feel really bad. I don't plan stopping Methimazole, but I don't want to continue to take too high a dose in the meantime based on how fast I'm falling.

To complicate matters, Endo forgot to taper me off my full hyperthyroid dose of beta-blocker after I went into the normal range, so I have had symptoms with that. I'm almost completely off it in 5 days. (almost went to ER because I was blacking out prior to that)

Here are my latest results from July 31, 2018

Dosage of Methimazole prescribed: 15 mg/day

TSH .04 (range .40 - 4.50)

FT4 1.2 (range .8 - 1.8)

FT3 2.6 (range 2.3 - 4.2)

Just 17 days ago, my dosage was cut 7 days after the test below from 20 mg to 15 mg.

June 14, 2018

TSH .01 (.40 - 4.50)

FT4 1.2 (.8 - 1.8)

FT3 3.5 (2.3 - 4.2)

Please help, I'm scared.

Endo takes awhile to get back to me after blood tests, so for 7 days I was on 20mg, then last 10 days before test was on 15mg. I was also on 20mg dose when my levels were 4 times the highest end of the ranges above, and my TSH was .006. I first started treatment the end of April. My Endo says she is giving me "excellent care" for my thyroid and if I have symptoms it's nothing to do with my thryoid. :(

I know thyroid levels take awhile to register after dosage changes, but apparently I am responding very well to the methimazole.

Should I take 10mg or 5 mg? I don't want to rebound, but wow. Any thoughts are appreciated!

4 Replies

Is the beta blocker you're taking Propranalol by any chance. If so, it inhibits conversion of T4 to FT3. This, combined with the Methimazole, will really bring your FT3 down fast. Get off the beta blocker and then the Methimazole can be adjusted.

in reply to Hidden

Thanks Hidden! I was on Metoprolol 25mg. Since last Friday, I’ve been trying to stop after calling afterhours Emergency line from almost passing out twice. Endo who covers that (my endo’s partner) said to just stop it - since I was in the normal range now, and would normally be taken off it when that happens. Said since only on it for 3 months wasn’t long enough to taper it. Stopped cold turkey Saturday. Went into tachycardia Sunday so took another full dose and then called my pharmacist. She said to taper off. Take a half dose for 3 days and then 1/2 dose every other day. I took a 1/2 dose on Monday and then decided not take one Tuesday. My blood pressure and pulse bounced up and down badly Monday & Tuesday. Saw Endo on Tuesday while in tachycardia so she thought I was going hyper again and talked about raising my Methimazole but would wait for blood test and yes to just stop Metropolol. Said none of my symptoms were due to Thyroid or beta blocker and her excellent care. I should have went to emergency room and to see my GP for my symptoms. She forgot about my beta blocker after my last tests, although she didn’t admit it- tried to say it was my GP’s fault since he originally prescribed it before I saw her- never mind her name is on the prescription after she raised and then lowered my dose the past 3 months. 😮 Took a quarter dose on Wednesday. No dose on a Thursday - just riding out the tachycardia. My blood pressure is good. Pharmacist said it might take up to 40 hours to completely leave my system. I will look up whether or not Metoprolol blocks the conversion of T4 to T3. Thank you so much! I’m still taking the 15mg Methimazole. Trying to be compliant with that, but just scared.

in reply to Hmc449

Just looked- Metoprolol does inhibit T4 to T3 conversion. It’s been 48 hours since my last dose, so hopefully it’s now out of my system. Planning on staying on 15mg Methimazole dose until I can see my GP next Monday. Fingers crossed I can make some T3 and dose won’t be too much until I see him.

I love this forum. I’ve learned so much here and am really grateful!

in reply to Hmc449

Hope you feel better soon! There's not enough joined up thinking among health professionals. I had to tell my GP not to put me on Propranalol as it affected FT3. he hadn't got a clue! My old GP told me that they only get about half a day's training at med school on thyroid.

This forum is excellent. I always research everything before taking other meds.

Take care


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