ESPN 50th Annual Meeting

ESPN 2017


 
An unusual case of adipsic diabetes insipidus
ALIZEE MICHEL 1 MARTIN AUGER 1 FERIEL FORTAS 1 IULIA STOICA 1 TIM ULINSKI 1 JEAN DANIEL DELBET 1

1- PEDIATRIC NEPHROLOGY UNIT, ARMAND TROUSSEAU HOSPITAL AND UNIVERSITY PIERRE AND MARIE CURIE, PARIS, FRANCE
 
Introduction:

 Objectives. To characterize hypernatremia in a suspicion of Rapid onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic dysregulation, Neuro-Endocrine Tumors (ROHHAD-NET) syndrome and to suggest a treatment.

Material and methods:

 We describe the case of a 6 year-old obese boy (60 kg, 135 cm) with a suspicion of ROHHAD-NET syndrome and a severe and unexplained hypernatremia.

Results:

At admission, our patient presented with hypernatremia (154 mmol/L), a plasmatic hyperosmolarity of 332 mosmol/L and a hypotonic polyuria (207 mosmol/l) which was suspicious for diabetes insipidus (DI). After a water deprivation test, natremia increased to 160 mmol/l with a plasmatic osmolarity of 346 mosmol/L and, surprisingly, a urinary osmolarity of 535 mosmol/L, suggesting remaining endogenous vasopressin secretion. Plasmatic vasopressin values (1.47 pg/ml - 1.76 pg/ml) were low and inappropriate for natremia which ranged between 152 and 160 mmol/L, strengthening the diagnosis of partial central DI.

The absence of thirst despite severe hypernatremia suggests a specific type of DI known as adipsic DI. The hypothalamic dysfunction has been described in ROHHAD-NET syndrome. Our patient seems to have characteristics of both entities.

Desmopressin treatment resulted in a decrease of natremia to 146 mmol/L and urinary osmolarity increased to 822 mosmol/L. No genetic mutations in genes linked to monogenic obesity and pituitary deficiency including PCSK1 were identified.

Conclusions:

Hypernatremia seems to be a component of ROHHAD-NET syndrome, even if the pathophysiological mechanism has not yet been identified. We report the case of a boy with a condition compatible with ROHHAD-NET syndrome and central partial adipsic DI. Oral desmopressin treatment and free water access improve natremia and potential neurologic damage. Careful attention should be paid concerning the narrow gap between benefits and potential risks of desmopressin treatment and free water intake in such conditions.