 The investigators preliminary data strongly suggest that thrombocytopenia after cardiac surgery is linked to AKI and increased mortality. In a prospective study of 100 patients undergoing coronary artery bypass graft CAGB surgery, the investigators will define platelet activation and consumption as the likely cause of this thrombocytopenia, and establish the association between platelet activation in general with markers of mast cell activation, systemic inflammation, and AKI. 