To further investigate this the investigators will perform a retrospective review using the renal transplant database to collect data regarding pre-operative diagnoses, co-morbidities, and method of dialysis used in the pre-transplant period. Pre-operative serum sodium level will be compared to post-operative serum sodium levels. Data including post-operative complications, need and reasons for post-operative dialysis, and hospital course will also be collected. Once the data are analyzed and a primary source or sources are identified as causative agents for post-operative hyponatremia, an intervention to prevent a decline in serum sodium post-operatively will be planned for future study.