Hypernatremia is characterized by high levels of which electrolyte in the blood?

• A. Potassium
• B. Sodium
• C. Calcium
• D. Magnesium

Answer: (B)

Hypernatremia means there is too much sodium in the blood. Sodium is the main extracellular positive ion and the key determinant of serum osmolality. When its concentration rises above normal, the extracellular fluid becomes hyperosmolar, pulling water out of cells. This cellular dehydration, especially in brain cells, can lead to confusion, lethargy, seizures, or coma if severe. The hallmark of hypernatremia is an elevated sodium level, not increases in potassium, calcium, or magnesium, which are different electrolyte issues. Treatment centers on correcting the water deficit and addressing the underlying cause, with careful monitoring to avoid rapid shifts in osmolality that could cause complications.