ABSTRACT
Cardiopulmonary bypass surgery has been linked with a number of postoperative complications. One of the frequently reported physiological alterations is the relative diuresis seen in the immediate post-op period. Rarely reported though is the development of full-blown diabetes insipidus in such patients. The etiology is unknown and has only been hypothesized in the past. We present the clinical course of a 54 year old male who developed transient diabetes insipidus post bypass surgery with subsequent recovery following exogenous vasopressin administration. The physiological alteration leading to the development of diabetes insipidus in a small fraction of bypass patients remains unknown. We propose that the variation in natriuretic peptide levels in the post-bypass period could account for the transient event