Rapid onset and rapid loss of renal function. Characterised by rise in serum creatinine and reduction in urine output. Although potentially reversible, it has a high mortality rate. AKI follows severe, prolonged hypotension, hypovolaemia or exposure to nephrotoxins.
• Prerenal - factors external to kidneys, they reduce systemic circulation causing a reduction in renal blood flow.
• Intrarenal - direct damage to kidney tissue, impairing nephron function. Acute tubular necrosis (ATN) is the most common intrarenal cause, caused by nephrotoxins. Indicated by urine sediments
• Postrenal - mechanical obstruction in urine outflow. Reflux of urine back into renal pelvis impairs kidney function by kidney dilation (hydronephrosis). Prolonged over 48h can cause tubular atrophy and irreversible kidney necrosis. e.g. prostate cancer