Laboratory testing reveals markedly elevated circulating triiodothyronine (T3) and thyroxine (T4) levels in a patient with hyperthyroidism. Which additional laboratory finding would most likely accompany this condition?

• A. Elevated TSH concentration due to stimulation of the anterior pituitary
• B. Increased TRH release caused by enhanced hypothalamic activity
• C. Reduced secretion of TSH from the anterior pituitary
• D. Increased parathyroid hormone secretion secondary to thyroid stimulation

Answer: (C)