Re: hyper symtoms labs in "normal range"
Have they run thyroid antibodies on your DS? Also, I would request repeat testing of TSH & frees, a lab req. that I would hold & repeat at a time when he is having a flare, if he has some spells that are worse than others.
What sort of doc is your son seeing, and are you confident in the care he is getting? Is HE confident in the care he is getting? Does the doc looking after thyroid understand about the heart problem?
This is messier stuff ... your son is a young adult ... but various habits can contribute to increased uptake of T3. If your son has started smoking, or drinking alcohol, even beer, that can contribute. Certain street drugs also increase uptake. BUT, as far as I know, these things aren't the primary cause of hyperT, just things that can be avoided to improve the situation. Some people find that a low-iodine diet is helpful in reducing symptoms.