Post-Operative Water Load Following Transsphenoidal Pituitary Surgery
Post-Operative Water Load Following Transsphenoidal Pituitary Surgery
Delayed post-operative hyponatremia occurs in 5-20% of patients following pituitary surgery
 and typically occurs on post-operative day 5-10.This decline in sodium can occur rapidly and
 have serious consequences such as altered mental status, seizures, coma, and even death.
 Despite significant research into patient demographics and risk factors, the investigators
 have not been able to predict which patients will suffer from delayed post-operative
 hyponatremia to date. At the Barrow Neurological Institute, physicians currently utilize an
 outpatient screening protocol to monitor patients' sodium levels after surgery, but this has
 yet to be effective for reducing readmissions following pituitary surgery. The etiology of
 delayed post-operative hyponatremia has been linked to water and sodium dysregulation in the
 post-operative period. It has been shown that post-operative day 1-2 sodium levels are
 statistically lower in patients who develop delayed hyponatremia, however, the numerical
 differences are not large enough to guide clinical management. The investigators propose that
 a water load on post-operative day 1 may expose underlying sodium/water dysregulation in the
 early post-operative period. This would improve physicians' understanding of the
 pathophysiology of post-operative hyponatremia, and it may help to serve as a screening tool
 for these patients in the future.
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.
Inclusion Criteria:

 -  18-80 years of age

 -  Functioning or non-functioning pituitary adenoma

 -  Sodium level 135-145 prior to surgery

 Exclusion Criteria:

 -  Enrolled in a separate pituitary research study

 -  Unable to provide his/her own consent

 -  Unable to take PO water

 -  Renal insufficiency

 -  Require maintenance corticosteroids pre-operatively

 -  TSH secreting tumor

 -  Patients who the treating surgeon deems a poor candidate for the water challenge

 -  Prisoners

 -  Pregnant women