IV Fluids and Sodium

Use isotonic fluid with appropriate KCl and dextrose (strong recommendation, evidence A): e.g., D5 0.9% NaCl or D5 lactated Ringer's, with KCl (20 mEq/L is common) once the patient has voided and kidney function is known. It halves the risk of hyponatremia compared with hypotonic fluid. D5 ½NS and D5 ¼NS are hypotonic and not first-line. Balanced fluids and saline are both acceptable.

Applies to 28 days to 18 years, ward and critical care. Not covered: neurosurgical disorders, congenital or acquired heart disease, liver disease, cancer, kidney dysfunction, diabetes insipidus, voluminous watery diarrhea, severe burns, neonates under 28 days or in the NICU, over 18 years. DKA and SIADH need individualized fluids.

Neonates under 28 days: outside the guideline; dosed by day of life and weight (often 60–80 mL/kg/day on day 1, advancing), with dextrose and usually no sodium for the first 24–48 hours.

First-line for mild to moderate dehydration: ORS 50–100 mL/kg over 3–4 hours in small, frequent sips (5–10 mL); nasogastric is fine if needed. Replace ongoing losses: under 10 kg, 60–120 mL per stool or vomit; over 10 kg, 120–240 mL. Use IV instead for altered mental status, intractable vomiting or ileus, shock or severe dehydration. Reduced-osmolarity WHO ORS: Na 75, K 20, Cl 65, citrate 10, glucose 75 mmol/L (245 mOsm/L).