A 52-year-old male with a history of acromegaly treated years ago presents with weight gain, puffy eyes, coarse dry skin, and a low free T4 with non-elevated TSH. Which drug would be indicated?

• A. Levothyroxine (Synthroid)
• B. Growth hormone
• C. PTU (Propylthiouracil)
• D. Bromocriptine (Parlodel)

Answer: (A)

The situation shows secondary (central) hypothyroidism: low free T4 with an inappropriately non-elevated TSH, in a patient with a history suggestive of pituitary disease (acromegaly treated in the past). In central hypothyroidism, the pituitary fails to provide adequate TSH, so the thyroid shortfalls despite a normal or low TSH level. The correct treatment is thyroid hormone replacement with levothyroxine to restore circulating free T4 levels to the mid-normal range. Since TSH is not a reliable guide in central hypothyroidism, you adjust the dose by monitoring free T4 rather than TSH. The other options wouldn’t address the underlying issue: growth hormone would not correct the hypothyroidism, PTU is used for hyperthyroidism, and bromocriptine is for prolactin issues or can be used for acromegaly but not for treating central hypothyroidism.