The National Kidney Disease Education Program (NKDEP) performed a survey of 6,350 representative U.S. laboratories (including physician office, hospital, independent, community clinic, health fair, insurance, public health, and other laboratories) regarding their serum creatinine and eGFR reporting practices in 2006-2007. As with any survey, there may be bias created by differential responses due to characteristics of respondents.

In the period October 2006-February 2007, the NKDEP (http://www.nkdep.nih.gov/) performed their own survey of 6,350 representative U.S. laboratories (including physician office, hospital, independent, community clinic, health fair, insurance, public health, and other laboratories) regarding their serum creatinine and eGFR reporting practices. The 10-item questionnaire included the following questions: “Does your lab report serum creatinine values for adults (18 years and older)?” (yes/no/not sure); “How many serum creatinine tests did your lab perform in 2005?”; “Does your lab ever report estimated glomerular filtration rates (eGFR) with serum creatinine determinations?”; (yes/no/not sure) “Under what circumstances does your lab report eGFR?” (with all measured serum or plasma creatinine determinations/only when specifically requested/other); “Which estimating equation do you use for your reports?” (4-parameter MDRD Study equation/6-parameter MDRD Study equation/Cockcroft-Gault/not sure/other; and “When reporting eGFR, at what point do you assign a ‘greater than’ (>) value?” (60 ml/min/1.73 m²/90 ml/min/1.73 m²/never (we always report an exact number)/other). A total of 4,002 laboratories responded to the survey (63% response rate), and 2,493 of these 4,002 laboratories responded that their laboratory reported serum creatinine and subsequently provided information on eGFR reporting.