What is the preferred fluid for resuscitation in a child with Acute Kidney Injury (AKI), normal saline (0.9% Sodium Chloride solution) or Ringer's lactate?

Fluid Resuscitation in Pediatric Acute Kidney Injury: Ringer's Lactate vs Normal Saline

For children with acute kidney injury requiring fluid resuscitation, use Ringer's lactate (or another balanced crystalloid) as the first-line fluid rather than normal saline, except in cases of severe traumatic brain injury where normal saline is preferred. 1, 2

Primary Recommendation

• KDIGO guidelines explicitly recommend isotonic crystalloids for volume expansion in patients at risk for or with established AKI, with emerging evidence favoring balanced solutions like Ringer's lactate over normal saline. 1, 2

• Balanced crystalloids reduce the risk of major adverse kidney events, hyperchloremic metabolic acidosis, and potentially mortality compared to normal saline in AKI patients. 2

• The SMART trial (n=15,802 critically ill patients) demonstrated that balanced crystalloids resulted in lower rates of major adverse kidney events compared to saline, with an absolute risk reduction of 1.1%. 2, 3

Mechanism of Benefit in AKI

• Normal saline contains 154 mmol/L of chloride, which is supraphysiologic and causes renal afferent arteriolar vasoconstriction, reducing glomerular filtration rate. 2, 4

• The high chloride load in normal saline induces hyperchloremic metabolic acidosis, which can worsen kidney function and complicate the clinical course. 1, 4

• Ringer's lactate has a balanced electrolyte composition with lower chloride content (108 mmol/L), avoiding these deleterious renal effects. 2, 3

Pediatric-Specific Evidence

• A 2024 meta-analysis of fluid resuscitation in children with severe infection and septic shock found that balanced crystalloids significantly reduced the risk of acute kidney injury compared to normal saline, though mortality rates were similar. 5

• In pediatric diabetic ketoacidosis, a 2025 randomized controlled trial (n=67) showed that Ringer's lactate led to faster resolution of acidosis and less hyperchloremia compared to normal saline. 6

• The rise in serum chloride was significantly higher with normal saline at 4 hours (8.7 vs 3.9 mmol/L) and 8 hours (10.8 vs 4.4 mmol/L) compared to Ringer's lactate. 6

Critical Contraindication: Traumatic Brain Injury

• Ringer's lactate must be avoided in children with severe traumatic brain injury or increased intracranial pressure. 2, 3

• Ringer's lactate has an osmolarity of 273-277 mOsm/L, making it slightly hypotonic compared to plasma (275-295 mOsm/L), which can worsen cerebral edema. 3

• In patients with severe head trauma, use normal saline (osmolarity 308 mOsm/L) as the isotonic crystalloid of choice. 3

Addressing Common Concerns About Potassium Content

• The potassium content in Ringer's lactate (4 mmol/L) should not be considered a contraindication in pediatric AKI patients with mild-to-moderate hyperkalemia. 2, 3

• This potassium concentration is similar to normal plasma levels and cannot create potassium excess when the patient's plasma potassium is higher than the fluid's potassium content. 3

• The only exception is rhabdomyolysis or crush syndrome, where potassium-containing fluids should be avoided due to the risk of marked hyperkalemia following reperfusion. 3

Practical Implementation Algorithm

1. Assess for contraindications:

   • Severe traumatic brain injury or increased intracranial pressure → Use normal saline 2, 3
   • Suspected rhabdomyolysis or crush syndrome → Use normal saline 3

2. For all other pediatric AKI cases:

   • Use Ringer's lactate as first-line fluid 2
   • Administer in 10-20 mL/kg boluses for resuscitation 1
   • Reassess hemodynamics frequently, targeting tissue perfusion markers (lactate clearance, urine output, mean arterial pressure) 2

3. If normal saline must be used:

   • Limit total volume to maximum 1-1.5 liters 2, 3
   • Monitor serum chloride and acid-base status closely 4
   • Switch to balanced crystalloid once contraindication resolves 4

Avoiding Fluid Overload

• Regardless of crystalloid type chosen, avoid excessive fluid administration as both Ringer's lactate and normal saline can cause volume overload and worsen AKI outcomes. 2

• Guide fluid administration by frequent hemodynamic reassessment rather than fixed volumes, targeting specific perfusion endpoints. 2