What laboratory finding is expected in a client with diabetes insipidus?

In diabetes insipidus, the body is unable to concentrate urine due to a deficiency of antidiuretic hormone (ADH), also known as vasopressin. This leads to excessive urination (polyuria) and increased thirst (polydipsia). As a result, patients often experience significant fluid loss, which can lead to dehydration and an increase in serum sodium levels.

Hypernatremia, or an elevated sodium concentration in the blood, is a direct consequence of the excess water loss because the body loses more water than sodium. This condition can be particularly dangerous as it may lead to symptoms such as confusion, seizures, or even coma if left untreated.

In contrast to hypernatremia, conditions such as hypokalemia and hypomagnesemia do not typically arise in diabetes insipidus. Hypertension is also not a common finding, since the fluid loss usually leads to a decrease in blood volume and, consequently, can cause low blood pressure rather than high blood pressure. Therefore, the expected finding in a client with diabetes insipidus is indeed hypernatremia.