Central diabetes insipidus in children and young adults: etiological diagnosis and long-term outcome of idiopathic cases.

Context: Central diabetes insipidus (CDI) is considered idiopathic in 20% to 50% of affected subjects.

Objective: The purpose of this study was to determine whether a systematic diagnostic workup could achieve better etiologic diagnosis in children and adolescents presenting with polyuria and polydipsia.

Design And Setting: This is a prospective study conducted at a tertiary referral center. Patients underwent clinical and endocrine evaluations every 6 months and neuroimaging every 6 months for 2 years and yearly for 3 years. Endocrine function and neuroimaging were also reassessed after adult height achievement.

Participants: A total of 85 consecutive patients with CDI were enrolled at a median age of 7.5 years; those with idiopathic CDI were stratified based on pituitary stalk thickness.

Main Outcome Measures: To establish the etiology of CDI, we determined the time lag between its onset and the specific diagnosis, the long-term impact on pituitary function, and the overall long-term outcomes.

Results: Of the subjects, 24 (28.2%) received an etiologic diagnosis at presentation and 11 (13%) within 2.5 years (n = 7 germinomas and n = 4 Langerhans cell histiocytosis), 7 (8.2%) were lost to follow-up, and 43 (50.6%) were considered to have idiopathic disease and were followed until the median age of 17.3 years. Neuroimaging identified 40 of 43 patients with self-limited inflammatory/autoimmune pituitary stalk thickness within the first 6 months, the severity of which was significantly correlated to pituitary dysfunction. The probability of >10-year-survival without an anterior pituitary defect was related to the severity of pituitary stalk thickness, and 53% showed permanent anterior pituitary defects. Three patients developed Langerhans cell histiocytosis and 1 developed Hodgkin lymphoma after a median of 9 and 13 years, respectively.

Conclusions: A diagnostic etiology was achieved in 96% of patients with CDI. Risk stratification based on the degree of pituitary stalk thickness is of prognostic value for long-term outcomes including permanent pituitary dysfunction. New guidance is provided for the management of these patients.