The sodium content of normal saline is which of the following?

• A. 0.075 mEq/mL
• B. 0.154 mEq/mL
• C. 0.500 mEq/mL
• D. 0.100 mEq/mL

Answer: (B)

Sodium content in normal saline reflects the sodium ion concentration in a 0.9% NaCl solution. Normal saline contains 9 g of NaCl per liter. 9 g NaCl is about 9 / 58.44 ≈ 0.154 moles per liter, which is 154 mmol/L. Since sodium has a valence of 1, millimoles equal milliequivalents for Na+, so this is 154 mEq/L. Per milliliter, that’s 154 mEq/L ÷ 1000 = 0.154 mEq/mL. So the sodium content is 0.154 mEq/mL.