A 39-year-old female presents to the clinic for a routine health maintenance
exam. The patient reports she is feeling nervous and anxious all the time with
frequent palpitations. On further questioning she reports having diarrhea and
has been losing weight. She has also noticed a change in hair and fingernail
growth and frequently feels warm while others are cold or comfortable. She
denies any history of depression or anxiety disorder and is not taking any med-
ications. On examination, her heart rate is 110 beats per minute. She has a
slight tremor and has increased reflexes in all extremities. A nontender thyroid
enlargement is appreciated in the thyroid region. Her TSH level is low at
0.1 mIU/mL. The patient is told that she has an autoimmune antibody process.
What is the most likely diagnosis?
What is the biochemical mechanism for this disorder?