Hyponatremia is characterized by a decrease in which electrolyte due to excess water?

Hyponatremia is characterized by a decrease in which electrolyte due to excess water?

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

Answer: (A)

Hyponatremia happens when there is too much water relative to sodium, diluting the sodium concentration in the blood. Sodium is the main extracellular cation that sets plasma osmolality; when excess water reduces its concentration, you get hyponatremia. So the electrolyte decreased due to excess water is sodium. Potassium, calcium, and magnesium aren’t primarily decreased because of excess water in the same way. Their disturbances arise from other factors such as shifts between compartments, hormonal or metabolic issues, or losses, rather than dilution by excess water.

Hyponatremia happens when there is too much water relative to sodium, diluting the sodium concentration in the blood. Sodium is the main extracellular cation that sets plasma osmolality; when excess water reduces its concentration, you get hyponatremia. So the electrolyte decreased due to excess water is sodium.

Potassium, calcium, and magnesium aren’t primarily decreased because of excess water in the same way. Their disturbances arise from other factors such as shifts between compartments, hormonal or metabolic issues, or losses, rather than dilution by excess water.