Current standards are for screening of all post-operative transsphenoidal pituitary patients for sodium abnormalities in the POD(post-operative day)7-14 window. At the Barrow Neurological Institute, physicians have instituted a universal screening protocol for all post-operative patients wherein all patients have a serum sodium level drawn on POD5-7 and attempts are made to manage mild to moderate hyponatremia on an outpatient basis.This screening protocol has effectively identified delayed post-operative hyponatremia, however, it has yet to reduce readmissions for hyponatremia in these patients. The researchers propose that implementing a water load test on POD1 may facilitate outpatient screening in three ways: 1) The water load may identify a subset of patients who have appropriate water and sodium regulation after surgery and do not require close monitoring of outpatient sodium levels. 2) The water load may identify a subset of patients who are at risk for delayed hyponatremia and would benefit from strict counseling and closer outpatient monitoring. 3) The water load may identify a subset of patients with a moderate to severe reduction in serum sodium in response to the water load, and these patients may benefit from further monitoring in the hospital prior to discharge. If any of these scenarios hold true, this may change the way physicians monitor and treat patients following transsphenoidal surgery in the future. Furthermore, this protocol could be readily expanded to other neurosurgery practices and could facilitate care for future patients undergoing transsphenoidal pituitary surgery.