Acute kidney injury or acute renal failure is a condition in which kidney function is compromised due to sudden injury. It can be caused by conditions effecting in three steps including pre-renal, renal or post-renal damage. AKI if not treated can progress to CKD. Possible complications include: hyperkalemia, hypo or hypernatremia, hypercalcemia, metabolic acidosis due to proton retention, pulmonary edema, hypertension, stroke, uremic encephalopathy, uremic pericarditis or CKD.