Which of the following is a cause of central (neurogenic) diabetes insipidus?

• A. Brain Tumor
• B. Hyponatremia
• C. Hyperglycemia
• D. Polycythemia Vera

Answer: (A)

Central diabetes insipidus happens when there isn’t enough antidiuretic hormone from the hypothalamus/posterior pituitary, usually because of damage to those areas. A brain tumor in the hypothalamic-pituitary region can disrupt production or release of vasopressin, leading to the large-volume, dilute urine and increased thirst characteristic of central DI.

Hyponatremia isn’t a feature of central DI—it would reflect too little water loss or excess water relative to sodium. Hyperglycemia causes osmotic diuresis from high glucose in the filtrate, not from AVP deficiency, so it doesn’t cause central DI. Polycythemia vera isn’t linked to AVP production or release. Thus, a brain tumor that injures the hypothalamic-pituitary axis best explains central diabetes insipidus.