From the Guidelines
The evaluation for Acute Kidney Injury (AKI) should include a comprehensive assessment of the patient's history, physical examination, laboratory tests, and imaging studies, with a focus on identifying the underlying cause and guiding appropriate management, as recommended by the most recent study 1.
Key Components of AKI Evaluation
- Obtain a detailed medical history, focusing on recent illnesses, medications, and potential exposures, including family history, past medical history, drug history, and occupational exposure 1.
- Perform a thorough physical examination, including vital signs and volume status assessment, as well as blood pressure measurement and assessment of volume status 1.
- Order initial laboratory tests, such as:
- Serum creatinine and eGFR
- Urea and electrolytes
- Full blood count
- Urinary dipstick (qualitative albuminuria/proteinuria) 1
Additional Tests and Considerations
- Consider additional tests based on clinical suspicion, such as:
- Renal ultrasound to assess kidney size and structure
- Urine and blood cultures if infection is suspected
- Complement levels, antinuclear antibodies (ANA), and anti-neutrophil cytoplasmic antibodies (ANCA) if glomerulonephritis is suspected
- Creatine kinase (CK) if rhabdomyolysis is a concern 1
- Calculate the patient's estimated glomerular filtration rate (eGFR) using the CKD-EPI or MDRD equation, as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) consensus conference 1.
- Monitor urine output closely, aiming for at least 0.5 mL/kg/hour, as recommended by the American College of Radiology 1 and the Clinical Gastroenterology and Hepatology 1.
- Consider renal biopsy if the cause remains unclear or if rapidly progressive glomerulonephritis is suspected, as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) consensus conference 1.
From the Research
Evaluation of Acute Kidney Injury (AKI)
The evaluation of 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 2
- Assessment of volume status 3
- Institution of appropriate therapeutic measures designed to reverse or prevent worsening of functional or structural kidney abnormalities 3
Diagnostic Work-up
The diagnostic work-up for AKI includes:
- Measurement of serum creatinine level
- Complete blood count
- Urinalysis
- Fractional excretion of sodium
- Ultrasonography of the kidneys to rule out obstruction 4
- Clinical imaging, biological and immunological tests, along with optimal assessment of the need for renal biopsies 5
- Staging of AKI to stratify patients according to severity of the condition, based on serum creatinine level and urine output 6
Classification of AKI
AKI can be classified into prerenal, intrinsic renal, and postrenal etiologies, which is helpful in differential diagnosis and management 4, 6. The classification of AKI includes:
- Prerenal causes: decreased renal perfusion
- Intrinsic renal causes: drug-induced, contrast-associated, postoperative, and sepsis-associated AKI
- Postrenal causes: obstruction
Management of AKI
The management of AKI involves:
- Fluid resuscitation
- Avoidance of nephrotoxic medications and contrast media exposure
- Correction of electrolyte imbalances
- Renal replacement therapy (dialysis) for refractory hyperkalemia, volume overload, intractable acidosis, uremic encephalopathy, pericarditis, or pleuritis, and removal of certain toxins 4
- Management of the underlying etiology, when possible, and use of nondialytic and dialytic therapies 6