I'm not sure that can happen. Grave's is for life. How was your Grave's diagnosed? Did you have the Grave's antibodies tested: TRAB or TSI? Maybe you had Hashi's all the time but where in a 'hyper' phase when you were first tested and the doctor just assumed that it was Grave's?
Of course, you can have both at the same time, but the Grave's doesn't go away, it's always there.
Can you post your complete blood test: results and ranges? Just being 'in-range' isn't always good enough. It's where your result falls in the range that counts.
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