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Kidney Week

Abstract: TH-OR49

Barriers and Opportunities to Improve Variability in CKD Laboratory Methodology and Reporting: Results from the College of American Pathologists (CAP) 2019 Survey

Session Information

Category: Pathology and Lab Medicine

  • 1602 Pathology and Lab Medicine: Clinical


  • Vassalotti, Joseph A., Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Miller, Greg, Virginia Commonwealth University, Richmond, Virginia, United States

Variability in laboratory practices for estimated GFR (eGFR) and urine albumin-creatinine ratio (uACR) is a barrier to optimal CKD testing and interpretation by clinicians. The CAP serial surveys assess CKD laboratory methodology and reporting.


The CAP 2019 General Chemistry Survey conducted in December, included 9 questions regarding CKD tests.


Respondents included 7,105 laboratories (83.8% U.S. and 16.2% international) with a response rate of 87.5%. Laboratory reporting of eGFR based on serum creatinine has increased overall from 3% to 92% in CAP surveys between 2003 and 2019. The Figure shows 76% of laboratories were using an isotope dilution mass spectrometry (IDMS) traceable version of the MDRD 4-variable equation (45%) or the CKD-EPI equation (31%), but an incorrect equation was used for IDMS creatinine by 23% of the respondents, resulting in systematic over estimation of kidney function. Barriers for the pediatric population less than 18 years include only 10% of laboratories report the correct bedside Schwartz equation and 20% of laboratories applied an incorrect adult eGFR equation for children. The microalbumin term that KDIGO and KDOQI recommend be eliminated continues to be used by 64.5% of U.S. and 42.2% of international labs, see Table. Lastly, 12.6% of U.S., and 9.4% of international laboratories report only the urine albumin concentration without uACR, which is uniformly not recommended.


Laboratory variability is a call to action for nephrologists to collaborate with clinical laboratorians to improve appropriate CKD testing.

eGFR Equation Reporting

Albuminuria Reproting