Normal TSI and Graves

[OznamCiv]

I was recently diagnosed with Graves disease but my TSI levels seem to be in the normal range.  I don't show any physical signs of graves but my TSH and anti-thyroglobulin are out of whack.  I started taking 10 mg of methimazole right around the beginning of April 2011 which seem to have brought my TSH level back to normal.  Any help would be greatly appreciated.  Here is my blood work history:

11/11/2010
========
TSH - 1.49
T4 - 9.0
T3 Uptake - 34.0
Free T4 - 1.35
Free T4 Index - 3.1
T3 Total - 102

3/11/2011
========
TSH - 0.116
T4 - 9.4
T3 Uptake - 35.0
Free T4 - 1.67
Free T4 Index - 3.3
T3 Total - 130
Anti-Thyroglobulin - 292
Anti-TPO ab - <10

3/21/2011
========
TSH - 0.04
Free T4 - 1.6
Thyroglobulin AB - 237
Thyroid Peroxidase AB - < 10

5/17/2011
========
TSH - 2.35
Free T4 - 1.2
TSH Receptor Antibody - < 0.90
TSI - 47

[OznamCiv]

Thanks for responding Dr. Lupo.

No uptake scan was taken nor was an ultrasound done.  My endo diagnosed Graves on blood work and physical exam.  His physical exam entailed checking my heart rate, looking for tremors and examining my neck.  I do have a small goiter that is not visible.

I has an episode today during exercise where my heart rate shot up shortly and I got dizzy.  The dizziness lasted all day.  In fact I still do fell dizzy.  I contacted my endo and had a blood test done.  I should get the results shortly.

[Mark Lupo, M.D.]

You did have hyperthyroidism in 3/2011.
The Tg-Ab is not specific for Graves'.  TSI is positive in >90% but not all Graves' patients.
It's possible this was a mild transient thyroiditis.
Was there an I-123 uptake/scan?
Are there nodules or other changes on ultrasound.
Would decrease or taper off methimazole and follow thyroid function closely -- in fact, now would be a good time to retest.