What Are Some of the Risk Factors for Augmented Renal Clearance?

Bruce A. Mueller, PharmD, explains the risk factors for augmented renal clearance.

Bruce A. Mueller, PharmD, professor of Clinical Pharmacy, University of Michigan College of Pharmacy explains the risk factors for augmented renal clearance.

Interview transcript (slightly edited for readability):

The other end of the spectrum is augmented renal clearance (ARC). They actually have a superhuman amount of GFR. For years, we’ve talked about, “Does this exist? Does this not exist?” Every once in a while, you would find some [data] that indicated maybe this is true. The fact of the matter is that there are a fair number of patients who have ARC. They have GFRs that are 250mL per minute (where the normal is maybe closer to 100). [As clinicians] we underappreciated this for years; however, there are patients in the intensive care unit (ICU) who have this and there have been studies that have looked at every patient who comes into the ICU, measuring actual creatinine clearance by urine, to see these patients’ GFRs. There is a substantial fraction of patients who have ARC. This has implications on drug clearance, and we may need to dose more aggressively for drugs that are renally eliminated.

Whether or not the presence of ARC has an impact on patient outcomes [is up in the air.] For every study that finds that it does, you can find another study that finds that it doesn’t. But, it stands to reason that if you are getting rid of antibiotics faster, and antibiotic serum concentrations may be lower, that’s a problem.

In terms of which patients would be at greatest risk of ARC; these patients will be younger (<50 years of age); patients who don’t have any other organ failure. If they are otherwise healthy individuals, but they have something that brings them into the surgical intensive care unit—which is the place we see a lot of ARC—you should have it in your mind, “I wonder what this patient’s GFR really is.” It might be worth performing something like a measured urine creatinine clearance, just to see if this might be a person in front of you who has a very rapid renal clearance, and maybe you need to dose your drugs differently.