RESUMO

Hypoalimentation is an important cause of hypernatremic dehydration in neonates; however, extreme values of plasma sodium make it necessary to investigate the differential diagnosis. We report the case of a 20-day-old newborn who was admitted with severe hypernatremic dehydration, with plasma sodium of 213 mEq/L and oliguric acute renal failure. The patient was treated with intravenous fluids for correction of dehydration and peritoneal dialysis for adequate sodium correction. During the etiological study, a 10-fold increase in the concentration of sodium in breast milk was detected. Peritoneal dialysis was an effective therapy in the management of the extreme hypernatremia with sodium correction within the recommended rate. At the 1-year follow-up appointment, the child had normal renal function, normal for age psychomotor development, and neurological physical was unremarkable. In conclusion, we report a case of an unusual extreme hypernatremia with discussion of the underlying pathophysiology and, more importantly, the effective treatment with a mixed approach with intravenous fluids and peritoneal dialysis.