Acute kidney injury is a sudden drop in kidney function over hours to days, seen as a rising creatinine or falling urine output. Causes are grouped as prerenal (low blood flow), intrinsic (damage to the kidney itself) and postrenal (blocked urine flow).
Key symptoms
- Less urine than usual, or none
- Leg swelling and shortness of breath from fluid overload
- Nausea, poor appetite and fatigue
- Confusion in severe cases
- Recent vomiting, diarrhea, contrast dye or kidney-toxic drugs
What you find on exam
- Volume status: dry mucous membranes and low blood pressure, or edema and crackles
- Distended bladder or enlarged prostate
- Rash or joint findings that suggest systemic disease
- Pericardial rub or confusion from uremia
Tests
- Creatinine and BUN compared with baseline; electrolytes, especially potassium
- Urinalysis with microscopy: muddy brown casts, red cell casts or protein
- Urine sodium or fractional excretion of sodium
- Bladder scan and renal ultrasound to rule out obstruction
Treatment basics
- Treat the cause: fluids for low volume, a bladder catheter for obstruction
- Stop or adjust kidney-toxic drugs such as NSAIDs, aminoglycosides and ACE inhibitors
- Track intake, output and daily weight
- Correct high potassium and acidosis
- Dialysis for refractory high potassium, acidosis, fluid overload, uremia or toxins
Red flags
- Potassium above 6.0 mmol/L or ECG changes
- Fluid overload with low oxygen
- Uremic signs: confusion, pericardial rub, bleeding
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.