Acromegaly is caused by the overproduction of which hormone?

• A. Growth hormone
• B. Prolactin
• C. Antidiuretic hormone
• D. Thyroid-stimulating hormone

Answer: (A)

Acromegaly is caused by overproduction of growth hormone, most commonly from a pituitary adenoma. Growth hormone acts on the liver to make IGF-1, which drives many growth-promoting effects. In adults, the long bones can’t lengthen because the growth plates are closed, so excess GH causes thickening of bones and soft tissues, leading to enlarged hands and feet, coarsened facial features, and organ enlargement. Metabolic changes like insulin resistance can occur as well. Diagnosis centers on elevated IGF-1 and a growth hormone level that fails to suppress with an oral glucose tolerance test, with imaging typically showing a pituitary tumor. The other hormones listed have different roles—prolactin mainly affects lactation and reproductive function, ADH controls water balance, and TSH regulates thyroid function—so they don’t produce the tissue overgrowth seen in acromegaly. If excess GH occurs before growth plates close, the condition is gigantism; after closure, it becomes acromegaly.