Microalbuminuria increases following open-heart surgery where coronary artery bypass grafting (CABG) is utilised.7 CABG activates an inflammatory cascade, which may increase capillary permeability and cause microalbuminuria. The increase in capillary permeability may induce exudation of proteins from the lung capillaries into the capillary–alveolar interspace and alveoli, causing the so-called postperfusion lung, which resembles pulmonary oedema. In a recent study, Loef et al. demonstrated that CABG potentiates transient renal failure and microalbuminuria.8