31-year-old woman comes to the office with a 3-month history of palpitations and weight loss. She weighs 110
kg (243 lb); 3 months ago, she weighed 118 kg (260 lb). There is no associated dysphagia, neck pain, or
hoarseness, and her menstrual periods have been regular. The patient was previously healthy and her family
history is unremarkable. She does not use tobacco or alcohol. The patient is sexually active with one partner and
uses a barrier method for contraception. Temperature is 36.7 C (98.1 F), blood pressure is 140/90 mm Hg, pulse is
102/min, and respirations are 20/min. The thyroid gland cannot be clearly felt on examination due to body habitus.
Ocular examination is unremarkable. Laboratory tests show an elevated serum free triiodothyronine and thyroxine
and low TSH. A urine pregnancy test is negative. Radioactive iodine scan reveals uptake of tracer only in the right thyroid lobe
Which of the following processes is responsible for this patient’s elevated thyroid hormone levels?
- O A. Antibody-stimulated thyroid hormone production
- O B. Autonomous thyroid hormone production
- 0 C. Exogenous thyroid hormone intake
- 0 D. Pituitary dysfunction
- O E. Release of preformed thyroid hormone
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