Endocrine Abstracts

Central diabetes insipidus (CDI) is rare in children and has a wide variety of causes. In children, the majority of central DI is acquired, but 30 to 50% is considered idiopathic. However, the natural history of isolated idiopathic central ID is unpredictable and germinoma should always be considered during the first 3 years of follow-up.

Case report: We report the observation of a 16 year old patient, in whom the diagnosis of idiopathic central diabetes insipidus was retained in front of a polyuro-polydipsic syndrome with hypotonic urines and a restriction test in favour of a complete deficit, without antehypophyseal involvement, the morphological exploration (hypothalamo-hypophyseal MRI) did not objectify any intrasellar process, nor thickening of the pituitary stalk with absence of visualization of the post pituitary. The etiological exploration came back without anomaly. The patient was regularly followed by hormonal and morphological evaluation every 6 months. During the follow-up, a corticotropic deficit appeared after 2 years and morphologically an intrasellar process 30×16×24 mm was found after 3 years of monitoring, in comparison with bHCG and apha protein not elevated. In this context the patient benefited from a surgical management, the anathomo-pathological study came back in favor of a dysgerminoma. The treatment was completed by chemotherapy and radiotherapy, the patient is currently in remission for 2 years.

Discussion: This observation reminds the necessity of strict surveillance of patients with a diagnosis of idiopathic retained central diabetes insipidus, This joins the cohort of D. Lorgi in 61 children with diabetes insipidus considered idiopathic at diagnosis and prospectively followed by regular imaging, 11 finally had a diagnosis of germinoma or histiocytiosis within 2.5 years.

Conclusion: Once a diagnosis of CID is made, an etiologic investigation is necessary to tailor management. Patients with CID of undetermined etiology (idiopathic CID) require long-term clinical, radiological and biological monitoring to detect a specific etiology in time.