Though the mechanism underlying this association between early hyponatremia and mild hyponatremia is not entirely clear, some authors propose that this mild, early post-transsphenoidal hyponatremia is actually a different entity altogether and not related to ADH release, but rather to excessive administration of hypotonic fluids during surgery and in the immediate postoperative period [37,66]. This evidence concerns the gene AVP and Hyponatremia.