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

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


Background: 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.

Methods: 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%].

Results: 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.

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

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Chromatography, Liquid / methods*
  • Female
  • Glomerular Filtration Rate*
  • Glutamine / analogs & derivatives
  • Glutamine / blood
  • Humans
  • Male
  • Middle Aged
  • Pseudouridine / blood
  • Reproducibility of Results
  • Tandem Mass Spectrometry / methods*
  • Threonine / analogs & derivatives
  • Threonine / blood
  • Tryptophan / blood


  • Glutamine
  • Pseudouridine
  • N-acetylthreonine
  • Threonine
  • Tryptophan
  • phenylacetylglutamine