The Association Between Hyponatremia and Reflux-Related Renal Injury in Acute Pyelonephritis

The kidney regulates sodium balance and is the principal site of sodium excretion. Sodium is unique among electrolytes because water balance, not sodium balance, usually determines its concentration. Although water balance is usually regulated by osmolality, volume depletion stimulates thirst, renal protection of water and ADH secretion. Volume reduction has priority over osmolality; volume depletion stimulates ADH secretion, even if a patient has hyponatremia. The aim of this study was to consider scar nephropathy in children with UTI and hyponatremia and compare it with children without hyponatremia. 200 children with pyelonephritis were included in this case–control study as case and control groups, respectively. Subjects were selected from children referred to the pediatric clinic of our hospital in Arak, Iran. Case group included children with hyponatremia and UTI (with VUR) and control group included children with UTI (With VUR) and normal serum sodium. Data was analyzed using SPSS ver.18 Among 200 (100%) children in both groups, 5 children (5%) had normal sodium and reflux nephropathy and 23 children had hyponatremia and reflux nephropathy. Hyponatremia in children with reflux nephropathy was significantly more common than children without reflux nephropathy. The observed correlation between reflux-related injury and hyponatremia necessitates evaluation of electrolytes in children with pyelonephritis.