In a post-operative patient with craniotomy experiencing extreme thirst and a urine output greater than 1000mls over two hours, what condition should you suspect?

In a post-operative patient who has undergone craniotomy, experiencing extreme thirst and a significant urine output exceeding 1000mls over a two-hour period, the most suspect condition is Diabetes Insipidus. This condition is characterized by an inability to concentrate urine, leading to excessive urination (polyuria) and increased thirst (polydipsia).

After a craniotomy, there is a risk of disruption to the hormonal regulation of fluid balance, particularly involving the antidiuretic hormone (ADH), also known as vasopressin. Injury or pressure on the pituitary gland can lead to insufficient production of this hormone, resulting in the kidneys excreting large volumes of dilute urine. Therefore, the symptoms of extreme thirst and high urine output align closely with the clinical presentation of Diabetes Insipidus, particularly in the context of post-surgical changes.

In contrast, conditions such as Diabetes Mellitus, Hyperglycemia, and Acute Kidney Injury have different presentations or mechanisms that would not primarily cause both extreme thirst and polyuria in this post-operative scenario. Diabetes Mellitus typically involves high blood sugar levels with associated symptoms but would not directly lead to such a drastic urine output in the absence of other complications. Hyperglycemia may lead