In June 2006, 2007, 2008, 2011-2013, 2017, and 2019, the College of American Pathologists (CAP) performed its General Chemistry Survey, in which all CAP-accredited laboratories that performed routine chemistries (representing an estimated 80% or more of US laboratories performing routine chemistries) were queried regarding their eGFR reporting practices (response rates were 60%, 76%, and 77% in 2007, 2008, and 2009, respectively). In a supplemental survey, laboratories were asked “Does your institution report an estimated Glomerular Filtration Rate (GFR) based on a serum or plasma creatinine measurement without measuring urine creatinine?” (yes/no); “If yes, when do you report the estimated GFR?” (with all measured serum or plasma creatinine determinations/only when specifically requested/other); and “If your institution reports an estimated GFR, what formula is used?” (4-parameter MDRD Study equation/6-parameter MDRD Study equation/Cockcroft-Gault/not sure/other). In the creatinine accuracy calibration survey, which is purchased by laboratories for self-assessment, CAP asked participants to state their creatinine calibration method: IDMS-traceable versus traditional calibration. Note that manufacturers were polled in June 2009; it was found that all major global manufacturers are currently only distributing IDMS-traceable serum creatinine methods (as of the end of 2009) in all markets they serve. All existing lots of older calibration reagents should be used up during 2010 (exceptions: the Siemens Dimension/Vista Jaffe method which will continue with its current calibration traceability and the Nova Biomedical blood gas instrument creatinine measurement). Some smaller manufacturers were not represented in the survey but all major North American and global manufacturers responded (Miller, 2009).