What is the sodium level in Lactated Ringer's (LR) solution?

Sodium Level in Lactated Ringer's Solution

Lactated Ringer's solution contains 130 mEq/L (or 130 mmol/L) of sodium. 1, 2

Composition of Lactated Ringer's Solution

Lactated Ringer's solution has the following electrolyte composition:

• Sodium: 130 mmol/L 3, 1, 2
• Potassium: 4 mmol/L 3, 1
• Chloride: 108 mmol/L 3, 1
• Calcium: 0.9 mmol/L 3, 1
• Lactate: 27.6 mmol/L 3, 1

Tonicity Characteristics

• Lactated Ringer's solution has an osmolarity of approximately 273-277 mOsm/L 3, 1, 2
• It is considered slightly hypotonic compared to plasma (which has an osmolarity of 275-295 mOsm/L) 3, 1
• In contrast, normal saline (0.9% NaCl) has an osmolarity of 308 mOsm/L and contains 154 mmol/L of sodium, making it isotonic 3, 1

Clinical Implications

• Due to its slightly hypotonic nature, Lactated Ringer's solution should be avoided in patients with severe head trauma or at risk for cerebral edema 3, 1, 4
• For brain-injured patients, 0.9% saline is the recommended crystalloid of choice as it is isotonic 1
• Despite being slightly hypotonic, Lactated Ringer's is recommended as a first-line balanced fluid for resuscitation in many clinical scenarios due to its electrolyte composition that more closely resembles plasma 1, 2
• When administering Lactated Ringer's solution, it's important to remember it already contains 4 mmol/L of potassium 3, 1

Comparison with Other Solutions

The sodium content in Lactated Ringer's (130 mmol/L) is lower than that of normal saline (154 mmol/L), making it more physiologically similar to plasma sodium levels (approximately 142 mmol/L) 3, 1

In clinical studies comparing Lactated Ringer's to hypertonic saline solutions:

• Hypertonic solutions typically contain higher sodium concentrations (250-268 mmol/L) 5, 4
• These differences in sodium concentration affect fluid requirements during resuscitation, with patients receiving hypertonic solutions generally requiring less total fluid volume 5, 4