From the Guidelines
For a patient with acute kidney injury (AKI) in the morning, I recommend a systematic approach starting with immediate assessment of volume status, vital signs, and urine output, as this is crucial in determining the cause and severity of AKI, and guiding appropriate management 1.
Initial Assessment
The initial assessment should include:
- Evaluation of volume status and vital signs
- Measurement of urine output
- Calculation of the patient's baseline GFR and determination of the AKI stage using KDIGO criteria
- Obtaining a thorough medication history to identify potential nephrotoxic agents
Laboratory Tests
Order basic labs including:
- BUN
- Creatinine
- Electrolytes
- CBC
- Urinalysis, which may include microscopy for casts and epithelial cells, chemistry, and biomarkers 1
Imaging Studies
Consider renal ultrasound to rule out obstruction, especially in older patients or those with anuria, as postrenal causes of AKI, although less common, can be readily identified and treated with imaging 1.
Management
- Ensure adequate hydration with isotonic fluids (typically normal saline at 10-20 mL/kg) if the patient is hypovolemic, but avoid fluid overload
- Monitor urine output closely, aiming for >0.5 mL/kg/hr
- Discontinue nephrotoxic agents such as NSAIDs, ACE inhibitors, ARBs, and certain antibiotics
- Arrange urgent nephrology consultation for possible dialysis if the patient has severe electrolyte abnormalities, acidosis, uremic symptoms, or volume overload unresponsive to diuretics
This approach is supported by the most recent guidelines and evidence, including the ACR Appropriateness Criteria for renal failure 1 and the AGA clinical practice update on the evaluation and management of acute kidney injury in patients with cirrhosis 1, and prioritizes the patient's morbidity, mortality, and quality of life as the primary outcomes.
From the Research
Morning Workup for Acute Kidney Injury (AKI)
The workup for AKI in the morning involves a thorough history and physical examination to categorize the underlying cause as prerenal, intrinsic renal, or postrenal 2.
- Initial evaluation includes:
- Laboratory work-up to measure serum creatinine level, complete blood count, urinalysis, and fractional excretion of sodium 3
- Physical examination to assess intravascular volume status and identify skin rashes indicative of systemic illness 3
- Ultrasonography of the kidneys to rule out obstruction, particularly in older men 3
- The history should focus on risk factors, including nephrotoxic drugs, and the physical examination should include determination of fluid volume status 4
- Urinalysis with microscopy can narrow the differential diagnosis 4
- Management of AKI involves fluid resuscitation, avoidance of nephrotoxic medications and contrast media exposure, and correction of electrolyte imbalances 3
Diagnostic Evaluation
The diagnostic evaluation can be used to classify AKI as prerenal, intrinsic renal, or postrenal 3.
- The Kidney Disease: Improving Global Outcomes (KDIGO) defines AKI as an increase in the serum creatinine (SCr) level of 0.3 mg/dL or more within 48 hours, an SCr level increase of 1.5 times or more of the baseline level within 7 days, or a decrease in urine output to less than 0.5 mL/kg/hour for 6 hours 4
- AKI severity is determined by the degree of SCr increase or decrease in urine output 4
Treatment and Referral
Treatment with fluid resuscitation or diuresis is guided by the volume status 4.
- Emergent referral to a nephrology subspecialist is recommended for patients with stage 2 or 3 AKI; patients with stage 1 AKI and a concomitant, decompensated condition; or if the etiology of the AKI is unclear 4
- Renal replacement therapy (dialysis) is indicated for refractory hyperkalemia; volume overload; intractable acidosis; uremic encephalopathy, pericarditis, or pleuritis; and removal of certain toxins 3