I was diagnosed with Graves Disease a year ago. I started with 20 mg of Methiamazole and responded right away. My family doctor managed me because the endocrinologist I saw right after diagnosis insisted that medication isn't effective and that I do RAI right away. My family MD has adjusted my medication several times. I became hypo twice (on 15 mg and 12.5 mg of Methiamazole last fall) and then since having one normal set of labs in January, my labs have not been responding well to Methiamazole. I had a flare of hyperthyroid in April, and have had to taper back up to 20 mg, which was the starting dose. Also, despite a year on medication, my TSI went from 334% when diagnosed to 553% in June.

I know that going off Methiamazole can cause relapse, but have not heard that the medication wouldn’t work while taking it.

I have a new endocrinologist who is mystified why my labs look like I’m not compliant on the medication, when in fact I really am. An ultrasound was consistent with Graves with no other abnormalities, and my eyes are OK. I want to avoid RAI or surgery but don’t know what to do next. I'm on a gluten free diet and reducing stress.

I would really appreciate any input you have. All the labs (normal ranges) are below. Thank you.

7/8/16

Free T-4 free 3.74 (0.82-1.77)
TSH <0.006 (0.45-4.5)
TSI 394% (l <140%)
Thyrogobulin and TPO Antibodies Normal
Began Methiamazole: Tapered from 5 to 20 mg over a week

8/12/16

Free T-4 0.91 (0.82-1.77)
Methiamazole lowered from 20 to 15 mg

9/10/16
Free T-4: 0.58 (0.82-1.77)
TSH 0.995 (0.45-4.5)
Methiamazole lowered from 15 to 10mg

10/15/16
Free T4 1.2 (0.82-1.77)
TSH 0.46 (0.45-4.5)
Methiamazole increased from 10 to 12.5 (MD concerned about low borderline TSH)

12/1/16
Free T-4 0.84 (0.82-1.77)
TSH 5.48 (0.45-4.5)
12.5 mg Methiamazole decreased to 7.5 mg

1/5/17 (only normal labs since diagnosis)
Free T-4 1.33 (0.82-1.77)
TSH 0.506 (0.45-4.5)
Methiamazole 7.5 mg

2/23/17
Free T-4 1.73 (0.82-1.77)
TSH 0.033 (0.45-4.5)
Methiamazole increased from 7.5 to 10 mg (MD concerned about low borderline T-4 and low TSH)

4/25/17
Free T-4 1.89 (0.82-1.77)
TSH <0.006 (0.45-4.5)
Methiamazole increased from 10 to 12.5 mg

5/11/17 Checked due to racing heart rate
Free T-4 2.02 (0.82-1.77)
TSH 0.006 (0.45-4.5)
Methiamazole increased from 12.5 to 15 mg

6-5-17 (new Endocrinologist)
Free T-4 1.14 (0.28-1.77)
TSH <0.006 (0.45-4.5)
Free T3 3.8 (2-4.4)
TSI 553% (<140%)
Methiamazole 15 mg

6/27/17
Free T-4 1.83 (0.82-1.77)
TSH <0.006 (0.45-4.5)
Free T3 5.0 (2-4.4)
Methiamazole increased from 15 to 20 mg

Hi,
I think you're responding to MMI but I'd guess that an environmental trigger, usually spring allergies or stress, may have caused the rise in TSI, which would cause your levels to rise and a need for more replacement hormone.
Could seasonal or even food allergies or aspartame be the problem? common allergens are soy, wheat and pretty much all grains, dairy and eggs. Some people don't notice improvement until they eliminate all grains and/or dairy.
There are people who do better on PTU than methimazole so that's another possibility. But since it's TSI rising and the cause of your levels rising it's likely something environmental that's the problem. Most everyone also benefits from the use of stress reduction techniques such as yoga, deep breathing exercises, biofeedback, meditation or even daily walks. Best, Elaine