A 28-year-old woman presents with a 2-week history of anterior neck and pharyngeal pain, accompanied by heat intolerance, palpitations, hyperhidrosis, and generalized fatigue. Physical examination reveals temperature 38°C, weight loss, moist skin, no exophthalmos, grade I thyroid enlargement with bilateral tenderness, no bruit, and fine tremor in both hands. If your initial diagnosis is correct, which of the following laboratory findings is most likely to be observed?