Which condition can lead to hypernatremia due to water deficit?

Hypernatremia, which is defined as an elevated sodium level in the blood, can occur when there is a deficit of water relative to sodium. Dehydration is the condition that leads to this imbalance. When the body loses more water than sodium, either through excessive sweating, diarrhea, or inadequate fluid intake, the concentration of sodium in the blood increases, resulting in hypernatremia.

In cases of dehydration, the primary issue is the loss of water; therefore, the remaining sodium becomes more concentrated. This phenomenon can occur in various settings, such as during hot weather, heavy exercise without fluid replacement, or when someone is unable to access fluids due to illness.

Other conditions listed, such as fluid overload and hypotonic fluid administration, would typically result in a dilutional effect on sodium levels, potentially leading to hyponatremia rather than hypernatremia. Acute kidney injury may cause various electrolyte disturbances, but it does not directly lead to hypernatremia due to water deficit specifically; instead, it can lead to fluid retention or other complexities. Thus, dehydration stands out as the condition that directly causes hypernatremia due to a relative deficiency of water relative to sodium in the body.