• The first and major change is to switch to a non-race-based equation using creatinine for calculation of eGFR. This is the 2021 CKD-EPI creatinine refit without the race variable equation. This follows the recommendation of multiple professional societies as well as committees within the University of Iowa Hospitals and Clinics. This also aligns with the Iowa City VA Hospital which made this switch in March 2022. The inclusion of race in eGFR equations has been a controversial topic over the last few decades. This calculation will be performed for all serum/plasma creatinine orders (including creatinine as part of chemistry panels such as Basic Metabolic Panel or Comprehensive Metabolic Panel) for adults 18 years and older. The result will appear below the creatinine value in Epic as “eGFRcr (CKD-EPI 2021)” in the ELECTROLYTE/BUN/CRT folder in Result Review in Epic.

• The second change is to introduce an eGFR calculation based on cystatin C. This uses the 2012 cystatin C-based CKD-EPI equation which does not contain any race-based variables. This calculation will be performed for all serum/plasma cystatin C orders. This will be resulted as a separate eGFR component below the cystatin C value in Epic as “eGFRcys (CKD-EPI 2012)”.

• The third change is to introduce an eGFR calculation that combines both creatinine and cystatin C. This uses the 2021 eGFRcr-cys(CKD-EPI) refit without race variable equation. This calculation will be performed for all serum/plasma specimens for which both creatinine and cystatin C are ordered. This will be resulted as a separate eGFR component below the cystatin C value in Epic as “eGFRcys-cr (CKD-EPI 2021)”. The two cystatin C-based eGFR results will be viewable in the CREATININE/CYSTATIN C/EGFR folder in Result Review, which will allow viewing and comparison of all 3 eGFR estimates (if performed).

Cystatin C-based equations represent an alternative to eGFR equations based on creatinine alone and may offer advantages in some clinical situations (e.g., spinal cord injury with skeletal muscle loss) that may impact creatinine-based equations.

As is the current practice, if eGFR cannot be calculated for a variety of reasons (e.g., creatinine measurement not determined, age or gender of patient not available in Epic, patient younger than 18 years old), then an eGFR component will not be posted.

The changes described above also only affect eGFR estimates for adult patients (18 years and older) posted in Epic and not other eGFR or creatinine clearance calculations that may be used in other contexts for specialized applications (e.g., Pharmacy dosing of medications).

Questions should be directed to Matthew Krasowski, MD, PhD, medical director of the Clinical Chemistry (384-9380, matthew-krasowski@uiowa.edu).