Hyponatremia due to renal salt wasting in a patient with partial central diabetes insipidus

• Published in: Acta pediátrica española Vol. 63; no. 2; p. 77
• Main Authors: Blasco, P Betrián, R. Cabrerizo de Diago, Cuadrado Martín, M, M.I. Justa Roldán, J. Mengual Gil1, C. Loris Pablo
• Format: Journal Article
• Language: English
• Published: Madrid Ediciones Mayo 01.02.2005
• Subjects: Case studies; Dehydration; Diabetes; Medical treatment; Pediatrics; Salt
• ISSN: 0001-6640; 2014-2986

Hyponatremia in association with diabetes insipidus usually corresponds to an overdose of desmopressin; nevertheless, there are other possibilities. We present the case of an 18-month-old boy who was referred to us with a 2-month history of polyuria, polydipsia and weight loss. His medical record and the results of physical examination and additional tests, including neuroimaging, were normal, except for the presence of hypo-osmolar polyuria (3 L). After dry diet and the administration of antidiuretic hormone (ADH), he was diagnosed as having partial central diabetes insipidus, and intranasal desmopressin therapy was begun. Six months later, he was admitted to the intensive care unit with severe dehydration associated with hyponatremia (Na: 108 mEq/L), seizures and polyuria, with fractional excretion of sodium of 3 mL/100 mL glomerular filtration rate (GFR). One month later, he presented a similar episode and oral salt supplementation was begun. Four months later, his polyuria and polydipsia had improved. Given the clinical and analytical improvement, the treatment was discontinued and the child remains asymptomatic one year later. Cerebral salt-wasting syndrome is characterized by marked diuresis and natriuresis, in the presence of hyponatremia and depletion of the extravascular space. Its pathogenesis has been attributed to the action of different natriuretic peptides, and it is not always triggered by an intracranial disease. In our case, we questioned whether the patient presented true transient partial central diabetes insipidus or, in contrast, primary polydipsia-polyuria with subsequent development of salt-wasting syndrome due to an imbalance in the ADH-natriuretic peptide axis.