What is the normal range for serum sodium (Na+)?

What is the normal range for serum sodium (Na+)?

• A. 120-130
• B. 135-145
• C. 140-150
• D. 125-135

Answer: (B)

Sodium is the main extracellular cation that helps set serum osmolality and balance fluid between compartments. The normal reference range is about 135 to 145 mEq/L. Values within this window indicate euvolemia and proper tonicity. If sodium falls below 135, you’re dealing with hyponatremia, which can lead to cerebral edema if significant or rapid. If it rises above 145, you’re in hypernatremia territory, which can cause dehydration and increased serum osmolality. So the range 135–145 is the standard normal range to memorize.

Sodium is the main extracellular cation that helps set serum osmolality and balance fluid between compartments. The normal reference range is about 135 to 145 mEq/L. Values within this window indicate euvolemia and proper tonicity. If sodium falls below 135, you’re dealing with hyponatremia, which can lead to cerebral edema if significant or rapid. If it rises above 145, you’re in hypernatremia territory, which can cause dehydration and increased serum osmolality. So the range 135–145 is the standard normal range to memorize.