It's Graves Disease.
Don't worry -- it's named after the doctor that discovered it, not the destination.
(more update to follow)
Here's what my wife wrote to my parents:
Matthew has been through a battery of tests this week. He's not really one for detail but today his doctor called and told us he has Graves disease. His thyroid is working 3x more than normal. He already has a prescription and now they need to determine the dosage that will help him the most. He will go back in 3 weeks and again in 6 weeks to check the dosage. The doctor did say that after 12-14 months there is a possibility of remission. If it doesn't go into remission after a couple of years of treatment they will have to do a procedure to kill part or all of the thyroid. Then his thyroid would be hypo(underactive). According to the doctor this is much easier/ better to treat, it's easier to add hormones then try to control too many of them. Thank you all for praying for us. It's been a pretty crazy fall for us. Keep praying that Matthew will begin to feel better soon instead of feeling like he's on speed all the time (his resting heart rate is 112). We love you all and wish we were closer in proximity when things like this happen.
and it doesn't feel like I'm "on speed all the time". It feels like I'm coming off a huge cup of expresso. Jittery and exhausted. Bleh.