Query Tip: Query for Acute Kidney Injury (AKI)

Jul 25, 2023

There may be instances where a coder will suspect the patient has acute kidney injury (AKI), but the physician has failed to document the diagnosis.  In another scenario, the physician may have made the diagnosis, but there is a question of clinical validity. In either case, a query would be justified.

What are some clinical indicators that could be used in either of these situations when formulating a physician query? Most facilities will use one of the following definitions of AKI when validating the diagnosis. The key element for a coder will be to determine the patient’s baseline creatinine (Scr).  Without that, it is impossible to apply the criteria.

Comparison of Recent Consensus AKI Definitions

AKI Stage Urine Outputa KDIGO AKIN RIFLE
1 <0.5 mL/kg/h for 6-12 h Scr to 1.5-1.9 × baseline over 7 d or ≥0.3 mg/dL absolute increase over 48 h Scr to 1.5-2 × baseline or ≥0.3 mg/dL absolute Scr increase within 48 h Risk: Scr to ≥1.5 × increase within 7 d, sustained for ≥24 h
2 <0.5 mL/kg/h for ≥12 h Scr to 2.0-2.9 × baseline Scr to >2-3 × baseline Injury: Scr to ≥2 × increase
3 <0.3 mL/kg/h for ≥24 h or anuria for ≥12 h Scr to ≥3.0 × baseline, or Scr increase to ≥4.0 mg/dL or initiation of RRT Scr to >3.0 × baseline, or Scr increase to ≥4.0 mg/dL (with increase of 0.5 mg/dL) or initiation of RRT Failure: Scr to ≥3.0 × increase or Scr increase to ≥4.0 mg/dL (with increase of 0.5 mg/dL) or initiation of RRT
        Loss: Complete loss of kidney function for >4 wk

SOURCE: https://www.ajkd.org/article/S0272-6386(17)31141-1/pdf


Other findings that may be used as clinical indicators of AKI include:

  • Confusion
  • Fatigue/Lethargy
  • Abdominal pain
  • Metallic taste in mouth
  • Elevated potassium (K)
  • Nausea/Vomiting/Diarrhea
  • Edema
  • Proteinuria
  • Metabolic acidosis
  • Abnormal GFR

Treatment for AKI is usually fluid resuscitation. But the coder should also look for correction of electrolyte imbalances, avoidance of nephrotoxic medications, such as some antibiotics and NSAIDS, as well as contrast media, or dialysis in the most serious cases.


The information contained in this query advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.

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