EM · Acute kidney injury

Acute kidney injury

Also known as AKI · Acute renal failure · Pre-renal uraemia · Acute tubular necrosis

Acute kidney injury (AKI) is an abrupt fall in glomerular filtration producing a rise in creatinine and/or a fall in urine output, classified by KDIGO (creatinine rise of at least 26.5 micromol per litre in 48 hours, or at least 1.5 times baseline within seven days, or urine output under 0.5 mL per kilogram per hour for six hours). Split by site into pre-renal (reduced perfusion, intact tubules), intrinsic (acute tubular necrosis is the emergency exemplar) and post-renal (obstruction). The bedside discriminator is the BUN-to-creatinine ratio over 20 to 1 and a fractional excretion of sodium under 1 per cent for pre-renal disease, against a ratio under 15 and FENa over 2 per cent for intrinsic disease. Management is to treat the cause, give a fluid challenge, stop nephrotoxins, and manage the complications — hyperkalaemia with calcium chloride intravenously first, then insulin-dextrose and salbutamol, and renal replacement therapy for the AEIOU indications. ACEM-primary, globally tagged.