Transient Polyuria Related to Central Diabetes Insipidus Caused by Lymphocytic Infundibulo-neurohypophysitis in a Patient Treated for Graves' Disease

A 45-year-old man was hospitalized because of weight loss, finger tremor, thirst, polydipsia and increased urinary frequency. He was diagnosed with Graves' disease (GD) and central diabetes insipidus (CDI). Magnetic resonance imaging revealed the enlarged posterior pituitary with thickened stalk. Histological examination obtained from biopsy of the pituitary revealed lymphocytic infundibulo-neurohypophysitis. He received treatment with thiamazole (MMI) for GD and desmopressin acetate (DDAVP) for CDI. However, DDAVP administration could be discontinued as GD was gradually improved. This course indicates that not only the recovered renal response to arginine-vasopressin but also the immunomodulative effects of MMI might attribute to the improvement of polyuria.