Just to add to obsg's post, and without wishing to overcomplicate the picture, if your thyroxine level is normal, your slightly raised TSH could indicate "Subclinical (Mild) Hypothroidism."
If this is the case, your quack will most probably just monitor the situation, with repeated blood tests every 6-12 months or so.
This is quite a common condition, probably as common as going grey/bald in old age.
From an aviation point of view, I'm unable to comment. Wouldn't have thought it'd be an issue, but the usual warning- check with the authorities.
