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?

Elevated TSH concentration due to stimulation of the anterior pituitary

Increased TRH release caused by enhanced hypothalamic activity

Reduced secretion of TSH from the anterior pituitary

Increased parathyroid hormone secretion secondary to thyroid stimulation