Which condition is associated with hypernatremia?

Hypernatremia, which refers to an elevated sodium level in the blood, can occur when there is an excessive loss of water relative to sodium or an increased intake of sodium without adequate water intake. Diabetes insipidus is particularly associated with hypernatremia because this condition results in the kidneys being unable to concentrate urine, leading to a significant loss of free water. As individuals with diabetes insipidus urinate large volumes of dilute urine, they can become severely dehydrated if they do not replace the lost fluids, resulting in an increased concentration of sodium in the blood.

In contrast, hypoaldosteronism can lead to hyponatremia due to sodium loss, while burns and diarrhea typically result in isotonic or hypotonic fluid losses, which can cause dilution of sodium rather than an increase in its concentration. Therefore, among the choices given, diabetes insipidus stands out as the condition most directly linked to hypernatremia due to its effects on water balance and retention.