MEERA LADWA ACUTE KIDNEY INJURY

WHAT IS ACUTE KIDNEY INJURY? A rapid fall in glomerular filtration rate (GFR) In practice, since measuring GFR is difficult, we use a rise in serum urea and creatinine within 48 hours to diagnose. Often associated with oligo-uria, but not always Occurs 15% of adults in hospital

CAUSES Pre-renal (common) --any cause of shock, e.g. sepsis, hypovolemia -any cause of reduced cardiac output e.g. cardiac failure, severe valvular disease -renal artery stenosis, hepato-renal syndrome -drugs, eg ACE inhibitors The mechanism is reduced renal perfusion, eventually resulting in acute tubular necrosis (ATN). This is potentially reversible.

WHAT IS THIS?

CAUSES Intrinsic renal (less common, but v important to recognise) - Tubular, eg Multiple myeloma, drugs (aminoglycosides, contrast), rhabdomyolysis - Interstitial nephritis eg penicillins, NSAIDs - Glomerular; -Hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP) ‘Rapidly progressive GN’ or ‘crescentic GN’ e.g. Goodpasture’s, Systemic vasculitides e.g. SLE, PAN, Wegener’s granulomatosis, microscopic polyangiitis

CAUSES Post-renal (common ) -obstruction of the renal outflow tract Eg. stones BPH Trauma or surgery Tumours of bladder and prostate Other pelvis malignancies e.g. ovarian

INVESTIGATIONS Urinalysis – for blood and/or protein. Red cell casts in urine = glomerulonephritis Urine Bence-Jones protein – for myeloma. ‘Renal screen’ – ESR, protein electrophoresis, ANA, ANCA, anti-GBM antibodies, C3/C4 USS of the renal tract – to look for obstructive uropathy Renal biopsy

TREATMENT Stop nephrotoxic drugs Assess volume status and optimise e.g. give fluids if hypovolemic and dehydrated. Treat the cause e.g. antibiotics in sepsis, relieve obstruction, immunosuppressants+ plasma exchange for RPGN Renal replacement therapy e.g. hemodialysis

INDICATIONS FOR HEMODIALYSIS IN AKI Hyperkalemia, not responding to medical management Pulmonary oedema, not responding to medical management Severe acidosis, not responding to medical management Uremic pericarditis or uremic encephalitis

CONCLUSIONS Acute kidney injury is common in hospitalised patients Patients with AKI with no clear cause should have US of the kidneys within 24 hours If a glomerulonephritis is suspected, contact renal specialist team as early as possible