Acute Kidney Injury in Chronic Kidney Disease

Initial Evaluation and Management

The American Journal of Kidney Diseases recommends promptly evaluating all patients with AKI superimposed on CKD to identify reversible causes, stage the severity, monitor kidney function closely, and plan for 3-month follow-up to assess for progression to advanced CKD or development of acute kidney disease (AKD) 1, 2
The Kidney International guidelines suggest identifying reversible causes including volume depletion, nephrotoxic medications, urinary obstruction, and infection, and performing renal ultrasound to exclude obstructive uropathy 1, 3
Review and discontinue nephrotoxic agents when possible, as this remains a critical intervention even in the subacute phase, according to Kidney International 4
Assess volume status and perfusion pressure, particularly relevant in cardiorenal syndrome, as recommended by Kidney International 4
Consider kidney biopsy for unresolving AKI/AKD when the etiology remains unclear, as this may reveal underlying glomerular disease or other treatable pathology, according to Kidney International and Praxis Medical Insights 4, 5

Stage the AKI using KDIGO criteria, which includes Stage 1: SCr increase 1.5-1.9× baseline OR ≥0.3 mg/dL increase OR urine output <0.5 mL/kg/h for 6-12 hours, Stage 2: SCr increase 2.0-2.9× baseline OR urine output <0.5 mL/kg/h for ≥12 hours, and Stage 3: SCr increase ≥3.0× baseline OR SCr ≥4.0 mg/dL OR initiation of dialysis OR urine output <0.3 mL/kg/h for ≥24 hours, as defined by the American Journal of Kidney Diseases 1
Monitor serum creatinine serially to track trajectory, but recognize that urine output monitoring has limited utility in the subacute phase, according to Kidney International 4, 6
Adjust medication dosing based on current kidney function—this is a high-priority intervention, as recommended by Kidney International 4
Avoid hyperglycemia and consider alternatives to radiocontrast procedures when feasible, according to Kidney International 4

If kidney function does not recover within 7 days, the patient transitions from AKI to AKD, which extends up to 3 months, as defined by Kidney International and Nature Reviews Nephrology 4, 6, 7
AKD Staging (for patients 7 days to 3 months post-AKI) includes Stage 0A: No residual injury, but kidney remains vulnerable, Stage 0B: Evidence of ongoing injury/repair or loss of renal reserve, Stage 0C: SCr <1.5× baseline but not returned to baseline, Stage 1: SCr 1.5-1.9× baseline, Stage 2: SCr 2.0-2.9× baseline, and Stage 3: SCr ≥3.0× baseline OR SCr ≥4.0 mg/dL OR ongoing dialysis requirement, as defined by Nature Reviews Nephrology and the American Journal of Kidney Diseases 7, 8, 1

All patients must be evaluated at 3 months post-AKI to determine outcomes, according to the American Journal of Kidney Diseases 1, 2
Manage according to KDOQI CKD Guidelines (Guidelines 7-15) if CKD is present or worsened, as recommended by the American Journal of Kidney Diseases 1, 2
Consider the patient at increased risk for developing CKD and manage according to KDOQI CKD Guideline 3 for at-risk patients if no CKD is present, according to the American Journal of Kidney Diseases 1, 2
The intensity of follow-up should be stratified by AKD severity, with more severe AKD (Stages 2-3) prompting nephrology referral when feasible, as recommended by Nature Reviews Nephrology 8