ESPE Abstracts

Introduction: The management and follow-up of paediatric patients with arginine vasopressin deficiency (AVP-D) is challenging, particularly in infants (0-2 years). Few studies have examined the particularities of AVP-D in this age group.

Objectives: To describe clinical, laboratory, and demographic characteristics of AVP-D in infants at diagnosis and to describe the follow-up during the first years of life. To ascertain clinical, laboratory, and demographic characteristics that are associated with the occurrence of hyponatremia.

Materials and Methods: This 20-year retrospective cohort study evaluated the diagnosis and clinical evolution of all infants with AVP-D followed up in a referral university hospital.

Results: 65 infants (53,8% boys) were diagnosed with AVP-D, 38,4% in the neonatal period, and 46,1% in the first year of life. Most were born at term (80,6%) and had an adequate birth weight (72,9%). Most of them had comorbidities (83,1%) and were taking medication (92,2%). There was no need for the water deprivation test (WTD), and all diagnoses were confirmed by basal reduced urinary osmolality (Uosm) and elevated plasma osmolality (Posm) - median Uosm 164,4 mOsm/kg and median Posm 324,7 mOsm/kg. In 86,1% of them, hypernatremia occurred, and the mean natremia at diagnosis was 153,2 mmol/L. Central nervous system (CNS) malformations were the most frequent cause of AVP-D (55,4%), followed by infections (15,4%). Anterior hypopituitarism occurred in 78% of patients; in these, adrenocorticotropic hormone and thyroid-stimulating hormone deficiency were the most common (78,1% and 65,6%, respectively). Desmopressin (DDAVP) was started in 87,7% and maintained in 67,7% of patients; 10,8% were treated with fluid replacement alone. After the introduction of DDAVP, hyponatremia occurred in 63,3%, mainly in the youngest (neonates - 87,5%). The presence of comorbidity (P <0,01), the age at the diagnosis (P <0,01), and CNS malformations (P <0,01) were associated with hyponatremia. The mortality rate was high (74,2%), generally related to the underlying disease; 36,9% had brain death, and 60% died up to 2 years of age.

Conclusion: All infants with AVP-D presented elevated basal Posm and reduced Uosm, not requiring WDT for the diagnosis. Most of them presented CNS abnormalities. Before treatment, hypernatremia was frequent, and the majority needed DDAVP. Under DDAVP therapy, hyponatremia was common, especially during the neonatal period and in infants with other comorbidities and CNS malformations, suggesting that DDAVP prescription and monitoring should be cautious in these groups. Mortality was high in these patients and was generally associated with the underlying disease.