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Tufts study on how GFR’s are measured seeks feedback from kidney transplant centers

The Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) and the Chronic Kidney Disease in Children Study (CKiD) are trying to gather information on how GFR is measured (mGFR) in medical institutions. There is some concern on the relative accuracy of various mGFR methodologies that use exogenous filtration markers, because inaccuracies in mGFR lead to inaccuracy of various GFR estimating equations (eGFR) that are generated from them.  An understanding of the GFR measurement procedures used in clinical labs is a first step in addressing the issue. 

To our knowledge, there is currently no data on what methods that laboratories are using to measure GFR and the goal of this survey is to gather some preliminary information.  We anticipate that this information will be used for planning a NIH’s National Kidney Disease Education Program (NKDEP) Laboratory Working Group-sponsored meeting this coming fall. 

Completing this survey should take less than 5 minutes and less than one minute if you do not actually measure GFR using an exogenous filtration agent (e.g., iohexol, iothalmate, etc.).  Only one response per medical center is required, but please be sure that at least one person fills it out for your institution.  Thanks very much in advance for your cooperation.  If you have any comments or questions about the survey, please email Lesley Inker, MD at or John Eckfeldt, MD, PhD at

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