Initial Management of Acute Kidney Injury (AKI)
The initial management of AKI should include immediate identification of the cause, discontinuation of nephrotoxic medications, fluid resuscitation in hypovolemic patients, and close monitoring of kidney function with daily serum creatinine and electrolyte measurements. 1
Diagnosis and Staging
AKI is defined by:
- Increase in serum creatinine by ≥0.3 mg/dL within 48 hours, OR
- Increase in serum creatinine to ≥1.5 times baseline within 7 days, OR
- Urine output <0.5 mL/kg/h for >6 hours 1
AKI is classified into three stages:
| Stage | Creatinine Increase | Urine Output |
|---|---|---|
| 1 | ≥0.3 mg/dL or 1.5-1.9× baseline | <0.5 mL/kg/h for 6-12h |
| 2 | 2.0-2.9× baseline | <0.5 mL/kg/h for ≥12h |
| 3 | ≥3.0× baseline or creatinine >4 mg/dL | <0.3 mL/kg/h for ≥24h or anuria for ≥12h |
Initial Management Algorithm
Step 1: Immediate Interventions (First 24 hours)
- Review and discontinue all nephrotoxic medications (NSAIDs, aminoglycosides, contrast agents) 1
- Assess volume status through clinical examination, vital signs, and when indicated, echocardiography or CVP 2
- Initiate fluid resuscitation for hypovolemic patients using isotonic crystalloids rather than colloids 2, 1
- For patients with cirrhosis and AKI, consider albumin administration (1 g/kg/day for 2 days) 2
- Hold diuretics and beta-blockers in patients with cirrhosis and AKI 2
Step 2: Laboratory and Diagnostic Workup
- Measure serum creatinine, BUN, electrolytes, complete blood count, and calculate anion gap 1
- Perform urinalysis with microscopy and urine chemistry 1
- Obtain renal ultrasound, particularly in older men or when obstruction is suspected 1
- Conduct a rigorous search for infection (blood cultures, urine cultures, diagnostic paracentesis in cirrhotic patients) 2
Step 3: Management Based on AKI Stage
For Stage 1 AKI:
- Implement close monitoring with daily serum creatinine and electrolytes 1
- Maintain strict intake and output monitoring and daily weight measurements 1
- Adjust medication dosages based on current renal function 1
For Stage 2-3 AKI:
- All measures for Stage 1 AKI plus:
- Consider volume expansion with albumin (1g/kg) for 48 hours 1
- Consider nephrology consultation 1
- Manage electrolyte abnormalities (particularly hyperkalemia) 1
- Consider renal replacement therapy for:
- Refractory hyperkalemia
- Volume overload unresponsive to diuretics
- Severe metabolic acidosis
- Uremic symptoms 1
Special Considerations
Patients with Pre-existing CKD:
- More frequent creatinine monitoring (every 12-24 hours) 1
- Lower threshold for nephrology consultation 1
Patients with Cirrhosis:
- Withdraw diuretics and non-selective beta-blockers 2
- Administer albumin 1 g/kg/day for 2 days if serum creatinine shows doubling from baseline 2
- Perform diagnostic paracentesis to evaluate for spontaneous bacterial peritonitis 2
Monitoring and Follow-up
Complete and sustained reversal of AKI within 48-72 hours of onset is associated with better outcomes 2. Therefore:
- Monitor kidney function daily during acute phase
- Assess for resolution, new onset, or worsening of kidney disease at 3 months after AKI episode 1
- Adjust medications as kidney function recovers 1
Common Pitfalls to Avoid
- Delayed recognition of AKI - monitor high-risk patients closely
- Continued use of nephrotoxic medications - review medication list thoroughly
- Inadequate fluid resuscitation or excessive fluid administration - tailor to individual volume status
- Failure to identify and treat underlying infections - conduct thorough infection workup
- Delayed nephrology consultation for severe AKI - consider early consultation for Stage 2-3 AKI
Early identification of persistent AKI (continuing beyond 48 hours) is crucial as it frequently progresses to acute kidney disease and requires additional monitoring and intervention 2.