@beachbum76 I am not attempting to diagnose anyone. And, it seems I was right to mention it. @halleyanne wrote her T4 is high, which is an indication of Hyperthyroidism, usually caused by Graves disease. Her doctor thought prudent to check the same thing I did. T4 is not regularly checked on teens otherwise. If she had not been to the doctor, giving her something to think about and research symptoms, and maybe get her to talk to a doctor about it seems like it was a good idea. High metabolism is rewarded in America, thin, need less sleep, energetic, and so at first it might be ignored, or reinforced as a good thing. She is lucky her doctor actually took it seriously.
@halleyanne Definitely get it tested periodically. It could reguate on its own. Know that thyroid can cause psychological symptoms like anxiety and mood swings. Literally, when people are hospitalized for mental issues thyroid is a mandatory test that is done. People can appear manic (bi-polar) when really they just have a hyperactive thyroid. And, it can affect your heart. If you begin having a pounding or racing heart regularly, or you feel very spacey, sort of light headed, at times (which is likely blood pressure problems, usually will be very low with Graves, but can be the opposite) go to the doctor for another blood test. I am not talking about light headed like when you get up to fast, but just sitting or standing in the middle of the day when your should feel alert and stable, and suddenly you feel spacey.
Do not simply rely on your GP if things start to really go out of whack, go to an endocrinologist. Reducing caffeine is not going to help your underlying condition, it will only help with some of the outward symptoms.