Diagnosis of acute kidney injury: Kidney Disease Improving Global Outcomes criteria and beyond.

PURPOSE OF REVIEW: Acute kidney injury (AKI) is common. Clear criteria and accurate diagnostic tools are essential to diagnose AKI early and correctly. The aims of this review are to outline some of the pitfalls of the Kidney Disease Improving Global Outcomes (KDIGO) classification and to describe other traditional and novel tools to diagnose AKI.

RECENT FINDINGS: The KDIGO classification of AKI is based on changes in serum creatinine and urine output. Misdiagnosis of AKI can occur when using only the KDIGO criteria. Potential pitfalls are related to the fact that neither creatinine nor urine output are renal-specific. Other traditional tools to diagnose AKI are blood urea nitrogen, urine chemistry, urine microscopy and renal biopsy. New diagnostic tools, including novel AKI biomarkers and techniques to measure glomerular filtration rate in real time, are being developed and validated.

SUMMARY: Knowledge about the strengths and weaknesses of traditional diagnostic tests is essential to make the correct diagnosis of AKI. New tests and technical innovations offer the prospect of diagnosing AKI earlier and more accurately.