Acute Kidney Injury

By definition: rise in serum Cr of >0.3 mg/dl within 48 hrs or an increase of 50% serum Cr within 7 days or urine output <0.5 ml/kg/hr for > 6hrs

CAUSES – Categorized into
PRERENAL – hypotension, volume depletion (vomiting, sweating, GI loses, hemorrhage, burns), renal artery stenosis, heart failure, ischemic tubular necrosis
INTRARENAL – Contrast dye tubular necrosis, NSAIDs, Glumerulonephritis, Acute interstitial nephritis, vasculitis, multiple myeloma
POST RENAL – BPH, pregnancy, carcinoma, calculus, clot, stricture, neurogenic bladder

DIAGNOSTIC TESTING
a. Urine analysis – blood, protein, casts, crystals
b. Urine eosinophils – >1% suggest acute interstitial nephritis
c. FENa, BUN/Cr ratio [ Pre-renal >20, Renal <10, Postrenal 10-20]
d. CBC, CMP
e. Renal US – calculus, hydronephrosis
f. Renal doppler – renal artery stenosis
g. CK – if suspicion for rhabdomyolysis

TREATMENT
1. Find insulting agent / cause and stop exposure
2. Correct electrolyte imbalances
3. Furosemide for volume overload
4. Hydrate patient with IV fluids

References:
1. Kurland J. Acute Kidney Injury. 5 minute consult (2019)