Which condition is characterized by excessive loss of sodium?

Hyponatremia is the correct answer because it refers specifically to a condition in which there is a lower than normal concentration of sodium in the blood, often resulting from excessive loss of sodium. This can occur due to various conditions such as excessive sweating, diuretic use, or certain medical disorders affecting fluid balance.

In hyponatremia, the body retains too much water in relation to sodium, diluting sodium levels and leading to symptoms such as headache, confusion, seizures, and even coma in severe cases. The management of hyponatremia typically involves addressing the underlying cause and carefully restoring sodium levels to avoid complications.

The other conditions mentioned relate to different electrolyte imbalances: hyperkalemia refers to high potassium levels, hypernatremia indicates high sodium levels, and hypokalemia involves low potassium levels, neither of which are focused on sodium loss specifically. Understanding these distinctions helps clarify why hyponatremia is solely characterized by excessive sodium loss or dilution in the body.