Cranial irradiation--an unusual cause for diabetes insipidus.

Central diabetes insipidus frequently occurs due to tumours in the region of pituitary or hypothalamus or following surgical trauma to these regions. Rarely it has been reported following cranial irradiation. We report the case of a middle aged woman who underwent surgical removal of a frontal capillary hemangioblastoma and received cranial irradiation. She presented ten months later with features of diabetes insipidus which was confirmed to be of central origin. She responded well to desmopressin nasal spray. Radiation induced damage to the hypothalmo-pituitary axis presents usually with anterior pituitary hormone deficiencies, most commonly that of growth hormone. Presentation as central diabetes insipidus is very uncommon.