Identifying Electrolyte Imbalance: Hyponatremia

A 70-year-old patient is admitted to the hospital with signs of dehydration, including dry mucous membranes, decreased skin turgor, and confusion. The healthcare provider orders a laboratory test to assess the patient’s electrolyte status. The normal range for serum sodium levels is 135-145 mEq/L. If the patient's serum sodium level is found to be 128 mEq/L, this condition can be categorized as __________.