Overview
Definition
A sudden decrease in renal function, resulting in the retention of urea and other nitrogenous waste products and in the dysregulation of extracellular volume and electrolytes.
Epidemiology
Occurs in ~5-7% of all hospitalized patients and up to 50% of ICU patients.
Etiology & Risk Factors
- Prerenal (hypovolemia, heart failure, sepsis)
- Intrinsic (Acute Tubular Necrosis, Acute Interstitial Nephritis, Glomerulonephritis)
- Postrenal (BPH, kidney stones, foley catheter obstruction)
Clinical Symptoms
- Oliguria or anuria
- Edema
- Fatigue
- Confusion (uremia)
- Often asymptomatic in early stages
Clinical Approach
Diagnosis
- Increase in serum creatinine by ≥ 0.3 mg/dL within 48 hrs
- Increase in serum Cr to ≥ 1.5 times baseline
- Urine volume < 0.5 mL/kg/h for 6 hours
- FENa (Fractional Excretion of Sodium) to differentiate pre-renal from intrinsic
- Renal ultrasound (rule out obstruction)
Management
- Treat the underlying cause
- Optimize volume status (IV fluids if pre-renal)
- Avoid nephrotoxins (NSAIDs, contrast, aminoglycosides)
- Renal Replacement Therapy (Dialysis) if indicated (AEIOU criteria)
Complications
- Hyperkalemia
- Metabolic acidosis
- Volume overload / Pulmonary edema
- Uremic encephalopathy
- Progression to Chronic Kidney Disease