A 56-year-old woman is brought to the physician by her daughter because of generalized fatigue over the past 4 months. She has had a 7-kg (15-lb) weight gain over this period. She is alert and oriented to time, place, and person. Her temperature is 36°C (97.6°F), pulse is 54/min, and blood pressure is 122/80 mm Hg. Physical examination shows hair loss involving the lateral third of the eyebrows. There is delayed relaxation of the deep tendon reflexes of the knee and ankle. Which of the following laboratory tests is the most appropriate next step in evaluation of this patient's symptoms?

Question

A 56-year-old woman is brought to the physician by her daughter because of generalized fatigue over the past 4 months. She has had a 7-kg (15-lb) weight gain over this period. She is alert and oriented to time, place, and person. Her temperature is 36°C (97.6°F), pulse is 54/min, and blood pressure is 122/80 mm Hg. Physical examination shows hair loss involving the lateral third of the eyebrows. There is delayed relaxation of the deep tendon reflexes of the knee and ankle.  Which of the following laboratory tests is the most appropriate next step in evaluation of this patient's symptoms?

Quizplus · Accepted Answer

Eductional Objective: The thyroid releases thyroid hormone (triiodothyronine [T3] and thyroxine [T4]) in response to TSH from the pituitary, which is regulated by thyrotropin-releasing hormone (TRH) from the hypothalamus.  Thyroid hormone suppresses the secretion of TSH and TRH via negative feedback, and small changes in thyroid hormone levels cause large changes in TSH.  Serum TSH is the most sensitive test for primary hypothyroidism.

A 56-Year-Old Woman Is Brought to the Physician by Her