Radiation Therapy & Diabetes Insipidus: Understanding the Risk

The hypothalamus and pituitary gland at the base of the brain are highly sensitive to radiation. Radiation therapy to this region can damage the hypothalamic-pituitary-adrenal (HPA) axis, causing diabetes insipidus (DI).

Mechanism

Damage to the hypothalamus reduces secretion of antidiuretic hormone (ADH/vasopressin). ADH normally promotes water reabsorption in the kidneys. Without sufficient ADH, excessive water is lost in urine, causing:

• Dehydration
• Intense thirst (polydipsia)
• Frequent urination (polyuria)

DI is distinct from diabetes mellitus (sugar diabetes). It requires hormone replacement (desmopressin) and fluid management.