Possible mechanisms for hyponatremia are likely multifactorial, but include etiologies such as fluid overload (prime solutions, cardioplegia, and transfusions) (Darling et al. 2000), diuretic administration, impaired water excretion caused by the release of anti-diuretic hormone (Philbin et al. 1977), and CPB-related natriuretic effect (Sehested et al. 1997). This evidence concerns the gene AVP and Hyponatremia.