Central diabetes insipidus is due to impaired production of which hormone?

• A. Antidiuretic hormone (ADH)
• B. Insulin
• C. Calcitonin
• D. Aldosterone

Answer: (A)

Central diabetes insipidus results from insufficient production of antidiuretic hormone (ADH), which is made in the hypothalamus and released by the posterior pituitary. ADH normally acts on the kidneys to promote water reabsorption in the collecting ducts by increasing aquaporin-2 channels, concentrating urine. When ADH is deficient, the kidneys can't reabsorb water effectively, leading to large volumes of dilute urine and increased thirst. Insulin, calcitonin, and aldosterone regulate other body systems (glucose, calcium, and sodium/potassium balance, respectively) and do not control this water-conservation mechanism, so they don’t explain central DI. Therefore, impaired production of ADH best accounts for central diabetes insipidus. Desmopressin can be used to replace ADH in treatment.