What is the management approach for acute kidney injury?

Management of Acute Kidney Injury

The management of acute kidney injury requires immediate identification and treatment of the underlying cause, discontinuation of all nephrotoxic medications, careful fluid management based on volume status, and early consideration of renal replacement therapy when specific indications are present. 1

Immediate Assessment and Diagnosis

Diagnose AKI when serum creatinine increases by ≥0.3 mg/dL within 48 hours, increases ≥50% from baseline, or when urine output falls below 0.5 mL/kg/h for >6 hours. 2 This diagnostic threshold allows for early intervention before severe complications develop.

Critical Initial Workup

• Obtain kidney ultrasound immediately to rule out obstructive uropathy, particularly in older men with prostatic hypertrophy 1, 3
• Assess volume status through clinical examination looking specifically for signs of hypovolemia (dry mucous membranes, decreased skin turgor, orthostatic hypotension) versus volume overload (peripheral edema, pulmonary congestion, jugular venous distension) 1
• Perform urinalysis with microscopy to detect hematuria, proteinuria, or abnormal sediment that suggests intrinsic renal disease 2
• Calculate fractional excretion of sodium (FENa <1% suggests prerenal causes) and fractional excretion of urea (FEUrea <28.16% better discriminates prerenal AKI) 4
• Conduct rigorous search for infection including diagnostic paracentesis for spontaneous bacterial peritonitis, blood and urine cultures, and chest radiograph 2

Medication Management: The Foundation of AKI Treatment

Immediately discontinue all nephrotoxic medications including NSAIDs, hold diuretics, ACE inhibitors, ARBs, and nonselective beta-blockers. 2, 1 This is non-negotiable and must occur within hours of AKI diagnosis.

Drug Stewardship Protocol

• Implement a clinical pharmacist-led review to identify all nephrotoxic exposures and perform medication reconciliation 2
• Avoid the "triple whammy" combination of NSAIDs + diuretics + ACE inhibitors/ARBs, which more than doubles AKI risk 2, 5
• Adjust all medication dosages based on current estimated GFR and reassess frequently as kidney function changes 2, 1
• Monitor aminoglycoside levels to keep peak concentrations below 12 mcg/mL and trough levels below 2 mcg/mL if these agents are absolutely necessary 5
• Recognize that macrolide antibiotics (clarithromycin, erythromycin) combined with statins increase AKI risk from rhabdomyolysis due to CYP3A4 inhibition; use azithromycin instead if macrolide therapy is required 2

Fluid Management Strategy

The approach to fluid management depends critically on volume status and must be reassessed continuously as clinical conditions change.

For Hypovolemic Patients

• Administer isotonic crystalloid for initial resuscitation to restore renal perfusion 1, 3
• In cirrhotic patients with AKI showing creatinine doubling from baseline, give albumin 1 g/kg/day for 2 days (maximum 100 g/day) 2, 4
• Avoid hypotonic fluids which worsen hyponatremia 1

For Euvolemic or Volume-Overloaded Patients

• Switch to neutral or negative fluid balance once hemodynamic stabilization is achieved 6
• Recognize that fluid overload worsens outcomes by causing interstitial edema that delays renal recovery, impairs wound healing, and increases infection risk 6
• Consider earlier initiation of renal replacement therapy to achieve negative fluid balance rather than pursuing aggressive diuretic therapy in oliguric patients 1, 6

Critical Pitfall to Avoid

Do not attempt aggressive fluid resuscitation to "reverse" established AKI in non-hypovolemic patients, as this creates a vicious cycle of fluid overload worsening kidney function and leading to worse outcomes 2, 6. Oliguria has multiple etiologies beyond hypovolemia and does not automatically indicate need for volume replacement 2.

Indications for Urgent Renal Replacement Therapy

Initiate RRT emergently for: 1

• Severe oliguria unresponsive to fluid resuscitation
• Refractory hyperkalemia
• Severe metabolic acidosis
• Volume overload causing pulmonary edema or respiratory compromise
• Uremic complications (encephalopathy, pericarditis, pleuritis)
• Certain toxin ingestions requiring removal

Reassess the need for continued RRT daily as kidney function may recover 1

Monitoring Protocol

• Check serum electrolytes, BUN, and creatinine every 4-6 hours initially in severe AKI 1
• Maintain strict input/output measurements to track fluid balance 1
• Monitor for uremic complications including altered mental status, pericardial friction rub, and bleeding 1
• Assess for signs of fluid overload including weight gain, peripheral edema, and pulmonary congestion 1

Prevention Strategies for High-Risk Patients

Identify patients at elevated risk including those with pre-existing chronic kidney disease, diabetes, heart failure, sepsis, hypovolemia, recent cardiac surgery, or contrast exposure 3, 7

Specific Preventive Measures

• Counsel complete avoidance of alcohol use, especially in patients with cirrhosis, as alcohol causes volume depletion through diuresis and vomiting 2, 4
• Avoid large-volume paracentesis without albumin replacement in cirrhotic patients 2
• Ensure adequate hydration before administering contrast media and consider N-acetylcysteine in high-risk patients 5
• Use acetaminophen as the preferred analgesic for non-inflammatory pain instead of NSAIDs 5
• Avoid excessive or unmonitored diuretic use 2

Management During Recovery Phase

Continue nephrotoxin avoidance throughout the persistent phase of acute kidney disease (AKD) and exercise caution when reintroducing potentially nephrotoxic medications during recovery to prevent re-injury 2

Patient Education Components

• Educate patients to avoid over-the-counter NSAIDs and to consult their physician before taking any new medications 2, 1
• Instruct patients to use ACE inhibitors, decongestants, antivirals, antibiotics, and herbal products with caution 2
• Counsel on maintaining adequate hydration, especially during illness 5
• Teach recognition of symptoms requiring immediate medical attention including decreased urine output, significant edema, or confusion 2

Common Pitfalls in AKI Management

• Delaying RRT when clear indications exist increases mortality 1
• Failing to identify and address the underlying cause leads to continued kidney damage 1
• Overly rapid correction of severe hyponatremia can cause osmotic demyelination syndrome 1
• Inappropriate continuation of nephrotoxic medications during the recovery phase causes recurrent injury 2
• Neglecting to adjust medication dosages as kidney function changes during recovery leads to drug toxicity or therapeutic failure 2, 1