Progressive thirst and urinary frequency suggest dysfunction of which endocrine structure?

Progressive thirst and urinary frequency suggest dysfunction of which endocrine structure?

• A. Adrenal cortex
• B. Thyroid follicular cells
• C. Posterior pituitary gland
• D. Anterior pituitary gland

Answer: (C)

Regulation of water balance hinges on antidiuretic hormone (ADH) release from the posterior pituitary. ADH acts on the kidney collecting ducts to increase water reabsorption; when ADH release is impaired, you get dilute urine and compensatory thirst—classic diabetes insipidus. ADH is made in the hypothalamus but stored and released from the posterior pituitary, so dysfunction of this gland directly disrupts ADH release. The other glands listed regulate different hormones (metabolism, stress response, etc.) and do not explain the polyuria and polydipsia seen with ADH dysfunction.

Regulation of water balance hinges on antidiuretic hormone (ADH) release from the posterior pituitary. ADH acts on the kidney collecting ducts to increase water reabsorption; when ADH release is impaired, you get dilute urine and compensatory thirst—classic diabetes insipidus. ADH is made in the hypothalamus but stored and released from the posterior pituitary, so dysfunction of this gland directly disrupts ADH release. The other glands listed regulate different hormones (metabolism, stress response, etc.) and do not explain the polyuria and polydipsia seen with ADH dysfunction.