This study is designed to determine the cause of post operative hyponatremia in renal transplant patients at the Mayo Clinic of Florida. Recently, the investigators have noted a trend in post-operative hyponatremia (low serum sodium) in patients who are recipients of both living donor and cadaveric kidneys. To improve the quality of care of this patient population, the investigators propose the investigation of the sources of this decline in serum sodium levels to determine if this is preventable. The investigators propose that a potential source of post-operative hyponatremia may be related to intra-operative factors. Currently, the intravenous fluid of choice used intra-operatively is 0.45% normal saline. The investigators hypothesize that this fluid choice contributes to post-operative hyponatremia.