Lymphocytic Infundibuloneurohypophysitis as a Cause of Central Diabetes Insipidus

Central diabetes insipidus may be familial, secondary to hypothalamic or pituitary disorders, or idiopathic. Idiopathic central diabetes insipidus is characterized by selective hypofunction of the hypothalamic-neurohypophysial system, but its cause is unknown. We studied 17 patients with idiopathic diabetes insipidus, in whom the duration of the disorder ranged from 2 months to 20 years. Only four patients had been treated with vasopressin before the study began. All the patients underwent endocrinologic studies and magnetic resonance imaging (MRI) with a 1.5-T superconducting unit, and two patients had biopsies of the neurohypophysis or the pituitary stalk. Nine of the 17 patients had thickening of the pituitary stalk, enlargement of the neurohypophysis, or both and lacked the hyperintense signal of the normal neurohypophysis. In the remaining eight patients, the pituitary stalk and the neurohypophysis were normal, although the hyperintense signal was absent. The abnormalities of thickening and enlargement were seen on MRI only in the patients who had had diabetes insipidus for less than two years, and the abnormalities disappeared during follow-up, suggesting a self-limited process. In addition to vasopressin deficiency, two patients had mild hyperprolactinemia and nine had impaired secretory responses of growth hormone to insulin-induced hypoglycemia. The two biopsies revealed chronic inflammation, with infiltration of lymphocytes (mainly T lymphocytes) and plasma cells. Diabetes insipidus can be caused by lymphocytic infundibuloneurohypophysitis, which can be detected by MRI. The natural course of the disorder is self-limited., Central diabetes insipidus is a chronic disorder characterized by polyuria and polydipsia due to vasopressin deficiency. The disorder may be familial, idiopathic, or secondary. Familial diabetes insipidus is characterized by autosomal dominant inheritance and, at least in some families, mutations of the vasopressin-neurophysin II genes¹,². Secondary diabetes insipidus, the most common form of the disorder, is caused by tumors, infections, trauma, or other processes (such as histiocytosis and vascular lesions) that damage the hypothalamic-neurohypophysial system. Idiopathic diabetes insipidus, which accounts for 10 to 30 percent of cases of central diabetes insipidus,³,⁴ is characterized by selective hypofunction of…