What is the pH of Lactated Ringer's (LR) solution?

pH of Lactated Ringer's Solution

Lactated Ringer's solution has a pH of approximately 6.5, which is acidic compared to physiologic pH of 7.4. 1

Composition and pH Characteristics

• The commercially available formulation of Lactated Ringer's solution is manufactured with a pH of approximately 6.5, making it acidic relative to normal blood pH 1
• Despite this acidic pH, the solution contains 28 mmol/L of sodium lactate, which is metabolized to bicarbonate in the liver, providing buffering capacity once infused 2, 3

Clinical Significance of the Acidic pH

• The acidic pH of standard Lactated Ringer's solution (pH 6.5) does not adversely affect resuscitation adequacy or patient outcomes, even in hemorrhagic shock states typically accompanied by metabolic acidosis 1
• Research comparing standard Lactated Ringer's (pH 6.5) to a modified version with pH 7.4 found no significant differences in cardiac output, lactate levels, fluid requirements, or survival in hemorrhagic shock models 1
• The only occasional difference noted was slightly higher arterial pH values in patients receiving the pH 7.4 version, but this did not translate to any clinical benefit 1

Metabolic Effects After Infusion

• Once infused, the lactate component is rapidly metabolized at the same rate whether it is racemic lactate or L-lactate, increasing bicarbonate concentration and base excess in the blood 2
• A 30 mL/kg bolus of Lactated Ringer's solution causes a modest increase in serum lactate (mean 0.93 mmol/L), but this does not result in clinically significant hyperlactatemia in hemodynamically stable patients 3
• The buffering capacity provided by lactate metabolism more than compensates for the initial acidic pH of the solution 2

Common Pitfall to Avoid

• Do not avoid using Lactated Ringer's solution based on concerns about its acidic pH of 6.5—the lactate is converted to bicarbonate systemically, providing alkalinizing effects that outweigh the initial acid load 2, 1