57) ANSWER

B) Urine specific gravity.

Explanation

Diabetes insipidus presents with symptoms of increased urinary output and very dilute urine. Urinary specific gravity will measure the concentration of the urine. Blood glucose and BUN are unrelated to the issue of the question. ACTH levels are not routinely monitored in any client. The core issue of the question is knowledge of diabetes insipidus and methods to assess the status of this complication. Use nursing knowledge and the process of elimination to make a selection.