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Clin Chem. 2019 Mar;65(3):406-418. doi: 10.1373/clinchem.2018.288092. Epub 2019 Jan 15.

Validation of a Metabolite Panel for a More Accurate Estimation of Glomerular Filtration Rate Using Quantitative LC-MS/MS.

Author information

Metabolon, Inc., Morrisville, NC.
Departments of Epidemiology, Medicine and Biostatistics, Johns Hopkins University, Bloomberg School of Public Health and School of Medicine, Baltimore, MD.
Division of Nephrology, Tufts Medical Center, Boston, MA.
Icelandic Heart Association, Kopavogur, Iceland.
Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
Department of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
Metabolon, Inc., Morrisville, NC;
Division of Nephrology, Tufts Medical Center, Boston, MA;



Clinical practice guidelines recommend estimation of glomerular filtration rate (eGFR) using validated equations based on serum creatinine (eGFRcr), cystatin C (eGFRcys), or both (eGFRcr-cys). However, when compared with the measured GFR (mGFR), only eGFRcr-cys meets recommended performance standards. Our goal was to develop a more accurate eGFR method using a panel of metabolites without creatinine, cystatin C, or demographic variables.


An ultra-performance liquid chromatography-tandem mass spectrometry assay for acetylthreonine, phenylacetylglutamine, pseudouridine, and tryptophan was developed, and a 20-day, multiinstrument analytical validation was conducted. The assay was tested in 2424 participants with mGFR data from 4 independent research studies. A new GFR equation (eGFRmet) was developed in a random subset (n = 1615) and evaluated in the remaining participants (n = 809). Performance was assessed as the frequency of large errors [estimates that differed from mGFR by at least 30% (1 - P30); goal <10%].


The assay had a mean imprecision (≤10% intraassay, ≤6.9% interassay), linearity over the quantitative range (r 2 > 0.98), and analyte recovery (98.5%-113%). There was no carryover, no interferences observed, and analyte stability was established. In addition, 1 - P30 in the validation set for eGFRmet (10.0%) was more accurate than eGFRcr (13.1%) and eGFRcys (12.0%) but not eGFRcr-cys (8.7%). Combining metabolites, creatinine, cystatin C, and demographics led to the most accurate equation (7.0%). Neither equation had substantial variation among population subgroups.


The new eGFRmet equation could serve as a confirmatory test for GFR estimation.

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