Q: I am very confused about the diagnosis of acute renal injury/acute renal failure. I know that one of the issues is the lack of agreed upon definition of AKI/renal failure and my readings certainly have reinforced this. So, I have the following questions:
- We have been using the definition about an abrupt rise in serum creatinine of >0.5 as criteria for AKI/renal failure. (Some references even say 0.3 rise). Is this appropriate?
- What about the temporary rise of creatinine >0.5 which responds to hydration? Is this still AKI/failure?
- The Acute Kidney Injury Network (AKIN) method does address this issue to say “after hydration” but other articles do not even mention this and consider hydration the treatment of acute renal failure.
- Some time ago we received a coding correction from CMS with a check for an underpayment for a patient with dehydration, renal failure, and heart failure. The renal failure responded to hydration. The comment from CMS was that both conditions were POA and the primary diagnosis was not heart failure as submitted but renal failure.
A: Very good questions. It is confusing for a lot of reasons not the least of which is the serum creatinine is not like a troponin level as it does not come from the kidney. Having said that, a .3 rise in the creatinine is only useful in the hydrated state in AKIN criteria, and although some physicians use this to reflect AKI it actually maps to "risk" (not injury or failure) in the RIFLE criteria.
In my own practice, I only use a change of 200% to reflect AKI or query regarding chart reviews.
Hopefully in the near future, there will be biomarkers ( IL-18 or Cystatin -C ) available that will directly reflect kidney injury and will solve the problem.
Editor’s Note: William E. Haik, MD, FCCP, director of DRG Review, Inc., in Fort Walton Beach, FL, and a member of the ACDIS advisory board, answered this question. Contact him at Behaik@aol.com or by phone at 850/863-2110.