Why does radiation for a brain tumor place client at risk diabetes insipidus?

The hypothalamus and pituitary gland are located at the base of the brain and are very sensitive to radiation. Following radiation therapy to this region, the hypothalamic-pituitary-adrenal (HPA) axis may be affected, resulting in diabetes insipidus (DI). DI is caused by damage to the hypothalamus, resulting in decreased secretion of antidiuretic hormone (ADH). ADH controls water reabsorption by the kidneys, so when it isn’t present in high enough quantities, free water is lost in the urine, causing dehydration, increased thirst, and frequent urination.