What is the role of biomarkers 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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Answer

Creatinine elevation is a late marker for renal dysfunction and, once elevated, reflects a severe reduction in glomerular filtration rate (GFR). Consequently, a number of biomarkers are being investigated to risk stratify and predict AKI in patients at risk for the disease.

The most promising biomarker to date is urinary neutrophil gelatinase-associated lipocalin (NGAL), which has been shown to detect AKI in patients undergoing cardiopulmonary bypass surgery. [48]

Breidthardt et al studied a model that combined the markers plasma B-type natriuretic peptide (BNP) and NGAL and found it to be a strong predictor of early AKI in patients with lower respiratory tract infection. The presence of a BNP level of over 267 pg/mL or an NGAL level of greater than 231 ng/mL correctly identified 15 of 16 early AKI patients, with a sensitivity of 94% and a specificity of 61%. [49]

A study of adults on the first day of meeting AKI criteria found that urine protein biomarkers and microscopy findings offer a significant improvement over clinical determination of prognosis. In this study, the risk for worsened AKI stage or inhospital death was approximately 3-fold higher for upper values than it was for lower ones for NGAL, kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18), and microscopy score for casts and tubular cells. [50]

A prospective study of serum cystatin C as a biomarker for AKI after cardiac surgery found that the cystatin C level was less sensitive than the creatinine level for detecting AKI. However, confirmation by cystatin C level appeared to identify a subset of patients with AKI with a substantially higher risk for adverse outcomes. [51]

For more information, see Novel Biomarkers of Renal Function.


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