The smallest endocrine gland secretes which hormone?

• A. TSH
• B. PTH
• C. Calcitonin
• D. Aldosterone

Answer: (B)

The smallest endocrine glands are the parathyroid glands, and they secrete parathyroid hormone (PTH). PTH regulates calcium balance by raising blood calcium levels: it stimulates bone resorption, increases calcium reabsorption in the kidneys, and boosts production of active vitamin D to enhance intestinal calcium absorption. This makes PTH the hormone tied to the smallest endocrine glands. The other hormones come from larger glands: TSH from the pituitary, calcitonin from the thyroid, and aldosterone from the adrenal cortex.