A nurse is caring for a client who is at high risk for developing diabetes insipidus (DI) following a severe head injury. Which assessment finding indicates to the nurse that the client is developing DI?

A. Urine specific gravity of 1.028 (1.005 to 1.03): A urine specific gravity in this range is within normal limits, indicating concentrated urine. In diabetes insipidus, urine is typically very dilute with a specific gravity below 1.005, reflecting excessive water loss, so this finding does not indicate DI. B. Urine output of 250 mL/hr: Excessive urine output is a hallmark of diabetes insipidus, especially in the context of a recent head injury. High-volume, dilute urine (polyuria) occurs due to a deficiency of antidiuretic hormone or kidney insensitivity to it. This finding alerts the nurse to the early development of DI and the need for intervention. C. Serum sodium of 115 mEq/L (136 mEq/L to 145 mEq/L): Low sodium indicates hyponatremia, which is not typical of DI. In fact, DI usually causes hypernatremia due to free water loss, making this finding inconsistent with the expected laboratory changes in DI. D. Blood glucose of 198 mg/dL (less than 200 mg/dL): Mildly elevated blood glucose may indicate stress hyperglycemia but is unrelated to the pathophysiology of diabetes insipidus. Glucose levels do not provide a reliable indication of DI development.