You haven't got the story quite right, Indi. To oversimplify:
TSH is "Thyroid stimulating hormone", and goes UP when your thyroid level is too low. Like the TSH is working harder to thrash out the last bit of thyroid function.
Thyroxine is the actual level of thyroid hormone in the blood.
So: Thyroid too low = Low Thyroxine, High TSH. Treatment is Thyroxine pill. Pretty routine.
Thyroid too high = High Thyroxine, Low TSH. Treatment is anti-thyroid medication, or radiotherapy, or surgery. A little more complicated, but still routine.
Not a condition for major concern, either way.
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Graham MD. No expertise as regards flight status.