An Elderly Patient with Transient Diabetes Insipidus Associated with Lymphocytic Infundibulo-Neurohypophysitis.

We present the eldest case ever reported of central diabetes insipidus (DI) associated with infundibulo-neurohypophysitis. A 77-year old woman, who complained of recent development of excessive thirst, polyuria and polydipsia, was referred to our hospital. The daily urine volume was markedly increased to 6 L. DDAVP administration effectively reduced urine volume and increased urine osmolality. The loading test using high-osmolar sodium chloride showed impaired excretion of vasopressin discordant with plasma osmolar changes. The anterior pituitary function was normal. Pituitary magnetic resonance imaging (MRI) showed thickening of the pituitary stalk and a lack of high-intensity signal of the neurohypophysis on T1-weighted images, suggestive of lymphocytic infundibulo-neurohypophysitis. The thickness of pituitary stalk on MRI improved 6 months later. DI was controlled with DDAVP for 40 days. This was followed by stabilization of the daily urine volume to less than 2.5 L without DDAVP. Our case is the eldest case of central DI associated with infundibulo-neurohypophysitis. The rapid remission of pituitary changes on MRI provides an insight that spontaneously partial remission of central DI may occur, resulting in transient polyuria and polydipsia.