About 76% of responding laboratories reported using IDMS-traceable calibration in 2019; the proportion of responding laboratories has increased 15% since 2006. There has been a steady rise since 2006 in implementing IDMS-traceable creatinine by laboratories. Data before 2008 may be inaccurate because many laboratories were not aware that the manufacturer may have performed the recalibration. Because there are two different four-parameter MDRD Study equations, one for historical or traditional calibration1 and one for IDMS-traceable calibration,2 laboratories should be aware of the type of calibration being used. Because manufacturers have globally switched to the IDMS-traceable creatinine assay, this variable will likely not be tracked going forward.
1 Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of diet in renal disease study group. Ann Intern Med. 1999;130(6):461-70.
2 Levey AS, Coresh J, Greene T, et al. Chronic Kidney Disease Epidemiology Collaboration. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med. 2006;145(4):247-54.