Diabetes insipidus due to hypophysitis.

Central diabetes insipidus is a chronic disorder which in most patients occurs secondary to tumor, infection, trauma or other lesions. In about 20-30% of patients etiology is unclear, however a destructive autoimmune process in the hypophysis may play a role. We report the case of an 18-year-old girl with central diabetes insipidus. Vasopressin levels were typically decreased. Examinations performed 1.5 years after manifestation showed no pathologic changes on MRI and no additional endocrine disorder. MRI was repeated 1.5 years later whereon a thickening of the pituitary stalk as a typical sign of hypophysitis was apparent. No other reasons could be found for the vasopressin deficiency. The finding of hypophysitis in our patient 3 years after disease manifestation suggests that the characteristic MRI changes may take as long as 3 years to become apparent.