Which tests are performed in the workup of acute kidney injury (AKI)?

Updated: Dec 24, 2020
  • Author: Biruh T Workeneh, MD, PhD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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The following tests can aid in the diagnosis and assessment of AKI:

  • Kidney function studies: Increased levels of blood urea nitrogen (BUN) and creatinine are the hallmarks of renal failure; the ratio of BUN to creatinine can exceed 20:1 in conditions that favor the enhanced reabsorption of urea, such as volume contraction (this suggests prerenal AKI)

  • Complete blood count (can indicate infection; acute blood loss or chronic anemia; thrombotic microangiopathy)

  • Peripheral smear (eg, schistocytes such as hemolytic-uremic syndrome and thrombotic thrombocytopenic purpura)

  • Serologic tests: These may show evidence of conditions associated with AKI, such as in lupus nephritis, ANCA vasculitis or anti-GBM disease or syndrome

  • Complement testing: Pattern may indicate AKI related to endocartis or various glomerulonephritidites

  • Fractional excretion of sodium and urea in the setting of oliguria

  • Bladder pressure: Patients with a bladder pressure above 25 mm Hg should be suspected of having AKI caused by abdominal compartment syndrome

  • Ultrasonography: Renal ultrasonography is useful for evaluating existing renal disease and obstruction of the urinary collecting system

  • Aortorenal angiography : Can be helpful in establishing the diagnosis of renal vascular diseases, such as renal artery stenosis, renal atheroembolic disease, atherosclerosis with aortorenal occlusion, and certain cases of necrotizing vasculitis (eg, polyarteritis nodosa)

  • Renal biopsy: Can be useful in identifying intrarenal causes of AKI and directing targeted therapy

See Workup for more detail.

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