Risk factors for hyponatremia after hypotonic fluid infusion

Hypotonic maintenance i.v. fluids (IVF) pose a higher risk of hyponatremia than isotonic maintenance IVF, but isotonic maintenance IVF can result in excess sodium (Na) load in children. This study analyzed the incidence and risk factors for hyponatremia in children given hypotonic fluids with different Na concentrations and different maintenance rates.

We performed a retrospective analysis using medical charts of children aged 3 months-15 years. The children were normonatremic (Na ≥135 mmol/L and <145 mmol/L) before IVF, and given IVF containing 35 mmol/L Na at a 100% maintenance rate (Na 35) or fluids containing 84 mmol/L Na at a 70% maintenance rate (Na 84) for 24-48 h.

Of a total of 463 children, hyponatremia (Na <135 mmol/L) occurred in 46/275 children (17%) given Na 35, and 16/188 (9%) given Na 84 (P = 0.01). On multivariate logistic regression analysis, Na 35 (OR, 2.19; 95%CI: 1.04-4.62), low clinical dehydration scale (CDS) score before IVF (OR, 0.17; 95%CI: 0.06-0.49), and high body temperature 24-48 h after maintenance IVF (OR, 2.39; 95%CI: 1.79-3.18) were independent risk factors for hyponatremia.

Maintenance IVF with low Na concentration at a 100% maintenance rate, low CDS before IVF, and a high body temperature 24-48 h after maintenance IVF are independent risk factors for hyponatremia.