# PTU to Methimazole



## LisaD (Oct 18, 2011)

Hello - I'm new to the boards but not new to Graves. I was diagnosed 21 years ago and have been on PTU ever since. It has always kept my diease in check until about a year ago. For the last year my T3 levels have been inching upward to where now I am on 250mg of PTU twice a day and my levels are still high (T3 is 294 and normal reference is 80 - 204). I've never had enlarged thyroid glands either, but now they are noticeable.

I talked to my doctor tonight and he wants to switch me to Methimazole (20mg twice a day). I have been on PTU so long I am nervous to switch. Has anyone else switched? Would it be better to increase my PTU dose to three times a day instead of twice a day? He has called in my Methimazole prescription but I haven't picked it up yet. Any thoughts about Methimazole vs. PTU? Thanks in advance!!


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## Octavia (Aug 1, 2011)

Lisa, welcome!

Please forgive my ignorance, but what is PTU?

Octavia


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## LisaD (Oct 18, 2011)

PTU is the short name for Propylthiouracil (it's an anti-thyroid drug like Methimazole).

My other lab results were:
T4 - 8.5 (reference range is 5.0 - 12.5).
TSH - 0.006 (reference range is 0.350 - 4.500)
T3 Uptake - 42.0 (reference range is 22.5 - 37.0)
T3 - 294 (reference range is 80.0 - 204.0)

Thanks for any insight into PTU vs. Methimazole.


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## Andros (Aug 26, 2009)

LisaD said:


> Hello - I'm new to the boards but not new to Graves. I was diagnosed 21 years ago and have been on PTU ever since. It has always kept my diease in check until about a year ago. For the last year my T3 levels have been inching upward to where now I am on 250mg of PTU twice a day and my levels are still high (T3 is 294 and normal reference is 80 - 204). I've never had enlarged thyroid glands either, but now they are noticeable.
> 
> I talked to my doctor tonight and he wants to switch me to Methimazole (20mg twice a day). I have been on PTU so long I am nervous to switch. Has anyone else switched? Would it be better to increase my PTU dose to three times a day instead of twice a day? He has called in my Methimazole prescription but I haven't picked it up yet. Any thoughts about Methimazole vs. PTU? Thanks in advance!!


Titrating or changing your meds based on the Total 3 is not wise. Total 3 is bound, unbound and rT3 (reverse) hormone.

Free T3 and Free T4 are the only accurate measurement of the actual active thyroid hormone levels in the body. This is the hormone that is actually free and exerting effect on the cells. These are the thyroid hormones that count.

http://www.drlam.com/articles/hypothyroidism.asp?page=3

I sure hope your doctor is checking your liver enzymes as that is a very very long time to be on anti-thyroid meds.

Have you ever had RAIU (radioactive uptake scan) to check for cancer?

Your T3 uptake does indicate hyper, however!

T3 Uptake - 42.0 (reference range is 22.5 - 37.0)

T3 Resin Uptake (hyper if high)
http://www.nlm.nih.gov/medlineplus/ency/article/003688.htm

Why have you chosen to not have your thyroid ablated?

Welcome to the board! We are happy you are here and your case is interesting.


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## LisaD (Oct 18, 2011)

The PTU has always worked well for me so I never considered radioactive iodine or surgery. I'm guessing medications can stop working (especially after 20+ years!) so maybe changing to the Methimazole will work. I haven't switched over yet, I'm waiting to get my most recent lab results in the mail (the ones I posted were from Sept 1st). I want to check them against the ones from Sept 1st to see how much the T3 has gone up, depending I might call my doctor back and see if we can increase my dose (or remain at my current dose) but spread it out over 3 times a day instead of twice a day. I am nervous to change after so many years on PTU.


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## Andros (Aug 26, 2009)

LisaD said:


> The PTU has always worked well for me so I never considered radioactive iodine or surgery. I'm guessing medications can stop working (especially after 20+ years!) so maybe changing to the Methimazole will work. I haven't switched over yet, I'm waiting to get my most recent lab results in the mail (the ones I posted were from Sept 1st). I want to check them against the ones from Sept 1st to see how much the T3 has gone up, depending I might call my doctor back and see if we can increase my dose (or remain at my current dose) but spread it out over 3 times a day instead of twice a day. I am nervous to change after so many years on PTU.


Well; a person does not like to rock the boat, that is for sure!!

However, it would benefit you to get the FREE T3 and FREE T4 tests and also at the very least an ultra-sound and at the very best RAIU (radioactive uptake scan.)

Since you do have Graves'; do you have a goiter, exophthalmos, pretibial myxedema and thryotoxicosis? I know you have the last one but wondered about the others.

Glad you are here; we have some wonderfully helpful folks on this board.


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## LisaD (Oct 18, 2011)

LOL! I'm not sure what most of those things are. I do have enlarged thyroid glands for the past year (goiter?). The others I'm not sure. 
I'll post again after I get my lab results from last week. Thanks!


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## ctob (Sep 20, 2011)

Hi Lisa I was just diagnosed earlier last month that I've had Grave's for about a year and have been learning a lot since. I am also on PTU was 3 pills 3 times a day and now 2 pills 3 times a day and the doctor already informed me that he wants to switch to the methimazole as soon as he thinks it will be safe to do so. I know a study recently came out linking PTU to liver damage so I think my doctor feels the methimazole would be safer. I don't know, just my thought because my liver is already damaged from being hyper. That is a long time to have to take PTU and I agree with Andros about your liver enzymes and see how they are. Sorry that things are acting up again for you and things turn around soon for you.


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## LisaD (Oct 18, 2011)

I've been extremely fortunate that I've never had a problem with the PTU. The doctor always checks for liver function and I"ve had no problem.

Does anyone know if the 500mg of PTU I am on is equivalent to the 40mg of Methimazole he wants me to switch to? I know Methimazole stays in the body longer so maybe I only need a smaller dose.


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## ctob (Sep 20, 2011)

I would think your pharmacist would be a good person to ask about that. I am glad no problems for you on that medicine. It has been used for many decades as a treatment so it must be better than it is worse I think. I do seem to be doing well myself on the medicine and anything is an improvement from before.


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## Andros (Aug 26, 2009)

LisaD said:


> I've been extremely fortunate that I've never had a problem with the PTU. The doctor always checks for liver function and I"ve had no problem.
> 
> Does anyone know if the 500mg of PTU I am on is equivalent to the 40mg of Methimazole he wants me to switch to? I know Methimazole stays in the body longer so maybe I only need a smaller dose.


I looked it up:

Dosage and Administration
Adults 
PO 300 mg/day in 3 equal doses every 8 h initially. In patients with severe hyperthyroidism or very large goiters, initial dosage may be increased to 400 mg/day, occasionally up to 600 to 900 mg/day. The maintenance dosage is 100 to 150 mg/day in divided doses every 8 h.

http://www.drugs.com/ppa/propylthiouracil-ptu.html


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## kdsjen (Apr 25, 2011)

I've never been on PTU, but have been on Methimazole about 4 months and can honestly say that I've had no side effects... except maybe it's why my hair has been so dry? I was terrified to take it. It sat at the pharmacy and then in my medicine cabinet for a ridiculous amount of time before I got brave enough! I hope your switch goes as smoothly.


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## Andros (Aug 26, 2009)

kdsjen said:


> I've never been on PTU, but have been on Methimazole about 4 months and can honestly say that I've had no side effects... except maybe it's why my hair has been so dry? I was terrified to take it. It sat at the pharmacy and then in my medicine cabinet for a ridiculous amount of time before I got brave enough! I hope your switch goes as smoothly.


Glad to hear this is going well for you. What is your daily dose and how often do you get labs. I am sure your experience could help others.


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## kdsjen (Apr 25, 2011)

I take 10mg a day. (Is it mg?) I get labs once a month and so far, so good! Now, my levels have yet to come down AT ALL. But maybe it's coming? Or at least preventing them from rapidly rising? I *think* I feel better. Hand shakes are gone and I'm sleeping much sounder.


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