This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
[{'content': 'Which of the following statements about Diabetes Insipidus is true - \nSelect and explain. \nA. Urine osmolality should be > 300 mosm\\/L, B. Plasma osmolality should be < 280 mmol\\/L, C. Water deprivation test is required, D. Plasma osmolality should be > 300 mosm\\/L prior to H2O Deprivation test', 'role': 'user'}, {'content': "Answer: C \nExplanation: In diabetes insipidus, urine is not maximally concentrated (osmolality below 600 mOsm/kg) in the presence of increased plasma osmolality (greater than 300 mOsm/kg). The diagnosis can be confirmed or refuted by random simultaeous samples of blood and urine, but more often a dynamic test like water deprivation test is required. Reference : page 794 Davidson's Principles and practice of Medicine 22nd edition", 'role': 'assistant'}]