Acute Kidney Injury Diagnosis and Management

Definition and Classification

The Kidney Disease Improving Global Outcomes (KDIGO) classification stages AKI based on severity, with Stage 1 being an increase in serum creatinine 1.5-2.0 times baseline or ≥0.3 mg/dL within 48 hours, according to the American College of Cardiology 1
AKI is diagnosed when serum creatinine increases by ≥0.3 mg/dL within 48 hours or by ≥50% from baseline within 7 days, or when urine output is reduced below 0.5 mL/kg/h for >6 hours, as defined by the Clinical Gastroenterology and Hepatology society 2, 1

Initial evaluation should include review of medication history for nephrotoxins and assessment of volume status through physical examination, as recommended by the Kidney International journal 3, 2
Specialized testing such as urine microscopy and renal ultrasound can help identify the cause of AKI, according to the Kidney International journal 4, 3
Novel biomarkers like NGAL can be used to distinguish ATN from HRS in cirrhotic patients, as suggested by the Gut journal 5, 6

Discontinue nephrotoxic medications and ensure adequate hydration based on volume status assessment, as recommended by the Clinical Gastroenterology and Hepatology society 2, 5
For prerenal AKI, volume expansion with isotonic crystalloids or albumin may be necessary, according to the Kidney International journal 3
For HRS-AKI in cirrhosis, albumin and vasoconstrictor therapy such as terlipressin may be used, as recommended by the Clinical Gastroenterology and Hepatology society 2, 7

Follow patients after AKI episode with regular monitoring of kidney function, as recommended by the Kidney International journal 3
Avoid future nephrotoxic exposures and consider nephrology referral for stage 3 or higher AKI, according to the Journal of Hepatology 6

The Acute Disease Quality Initiative (ADQI) recommends that novel damage biomarkers, such as kidney injury molecule-1 (KIM-1), may be used to diagnose AKI even in the absence of serum creatinine changes or oliguria in appropriate clinical contexts, with a strength of evidence based on expert consensus 8
The combination of tissue inhibitor metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) predicts progression to severe AKI, with a moderate to high level of evidence based on observational studies 8, 9

The American College of Radiology recommends renal ultrasound to evaluate kidney size and rule out obstruction, particularly in patients with a history of stones, obstruction, frequent UTIs, or family history of polycystic kidney disease, with a moderate level of evidence based on expert opinion 10