From the Guidelines
The workup for Acute Kidney Injury (AKI) should begin with a thorough history and physical examination, followed by basic laboratory tests including serum creatinine, blood urea nitrogen (BUN), electrolytes, complete blood count, and urinalysis with microscopy, as recommended by the 2021 study on acr appropriateness criteria for renal failure 1.
Initial Evaluation
The initial evaluation of a patient with suspected AKI should include:
- A thorough history to identify potential causes of AKI, such as recent medication use, underlying medical conditions, and exposure to nephrotoxic agents
- A physical examination to assess for signs of volume depletion, hypertension, and other potential causes of AKI
- Basic laboratory tests, including serum creatinine, BUN, electrolytes, complete blood count, and urinalysis with microscopy
- Urine output monitoring, with oliguria (<0.5 mL/kg/hr) being a concerning sign
Differentiating Causes of AKI
To differentiate between prerenal, intrinsic renal, and postrenal causes of AKI, the following tests can be used:
- Calculate the fractional excretion of sodium (FENa) to help differentiate prerenal (FENa <1%) from intrinsic renal causes (FENa >2%) 1
- Urine protein-to-creatinine ratio to assess for proteinuria
- Renal ultrasound to rule out obstruction
- Specific tests based on suspected etiology, such as complement levels, ANCA, anti-GBM antibodies for glomerulonephritis, or myoglobin for rhabdomyolysis
Management of AKI
For patients with severe AKI, consider renal replacement therapy indications, including refractory hyperkalemia (>6.5 mEq/L), severe acidosis (pH <7.2), volume overload unresponsive to diuretics, uremic symptoms, or pericarditis, as recommended by the 2020 study on controversies in acute kidney injury 1.
Nephrology Consultation
Early nephrology consultation is recommended for complex cases or when the GFR drops by more than 30%, as this can help identify the underlying cause of AKI and guide appropriate management to prevent further kidney damage.
From the Research
AKI Workup
The workup for Acute Kidney Injury (AKI) involves a thorough history and physical examination to categorize the underlying cause as prerenal, intrinsic renal, or postrenal 2. The initial evaluation and management of AKI includes:
- Laboratory work-up
- Medication adjustment
- Identification and reversal of underlying cause
- Referral to appropriate specialty care
Evaluation and Initial Management
The evaluation and initial management of patients with AKI should include:
- Assessment of contributing causes of kidney injury
- Assessment of clinical course including comorbidities
- Careful assessment of volume status
- Institution of appropriate therapeutic measures to reverse or prevent worsening of functional or structural kidney abnormalities 3
Key Questions in AKI Management
Key questions in AKI management include:
- Is there a difference in prognosis between volume-responsive and volume-unresponsive AKI?
- Are there biomarkers that predict the severity and recovery of AKI?
- What is the best biomarker to assess prospectively whether AKI is volume responsive?
- What is the best biomarker to assess the optimal volume status in AKI patients? 3
Management of Patients at Risk of AKI
Management of patients at risk of AKI includes:
- Awareness campaigns and education for health-care professionals on diagnosis and management of AKI
- Avoidance of volume depletion, hypotension, and nephrotoxic interventions
- Use of electronic early warning systems where available
- Fluid management to aim for early, rapid restoration of circulatory volume, but limited after the first 24-48 hours to avoid volume overload 4
Emergency Department Management
Emergency department management of AKI includes:
- Clinical manifestation of AKI, including electrolyte abnormalities and metabolic acidosis
- Treatment strategies that target the underlying cause and avoid further insults
- Conservative management as the first line of treatment, with renal replacement therapy or hemodialysis used if conservative management fails 5
Updated Review on Pathophysiology and Management
An updated review on the pathophysiology and management of AKI in critically ill patients includes:
- Prediction and early detection of AKI using biomarkers and machine learning
- Aspects of pathophysiology and progress in the recognition of different phenotypes of AKI
- Prevention of AKI, including fluid management, kidney perfusion pressure, and the choice of vasopressor
- Supportive treatment of AKI and post-AKI risk of long-term sequelae 6