The first human normative ranges and biomarker performance of dimethylguanidino valeric acid isoforms in fatty liver disease

Pathology. 2024 Apr;56(3):391-397. doi: 10.1016/j.pathol.2023.10.006. Epub 2023 Nov 23.


We have recently determined dimethylguanidino valeric acid (DMGV) to be a novel biomarker of liver injury in non-alcoholic fatty liver disease (NAFLD) and an independent predictor of incident diabetes over a decade in advance. DMGV consists of two stereo-isomers, asymmetric dimethylguanidino valeric acid (ADGV) and symmetric dimethylguanidino valeric acid (SDGV). Here we report, for the first time, the upper limits of normal of both isomers in humans at the accepted 5.56% liver fat threshold for NAFLD, determined using in vivo magnetic resonance spectroscopy. We performed independent and blinded comparative analyses of ADGV and SDGV levels using two different liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods in (A) our laboratory, and (B) the New South Wales Chemical Pathology state laboratory, using unique columns, LC-MS/MS equipment, extraction protocols and normalisation approaches. Despite these differences, each laboratory reported consistent absolute concentrations across a range of liver fat percentages. We next determined the diagnostic performance of SDGV compared to ADGV in a cohort of 268 individuals with liver fat measurements. In derivation-validation analyses we determined rule-in/rule-out thresholds and the concentration of SDGV that provides optimal performance across sensitivity and specificity for the identification of NAFLD. In conclusion, we have herein determined for the first time the true human plasma reference range of both isoforms of an emerging novel biomarker of NAFLD, at the accepted upper normal threshold of liver fat. We have also identified that SDGV is the isoform with the best diagnostic performance and determined the optimal cut-point for its detection of NAFLD.

Keywords: ADGV; Liver fat; SDGV; biomarkers; diagnosis; liquid chromatography; magnetic resonance spectroscopy; metabolic dysfunction-associated steatotic liver disease; non-alcoholic fatty liver disease; reference values; tandem mass spectrometry.

MeSH terms

  • Biomarkers
  • Chromatography, Liquid
  • Humans
  • Liver / pathology
  • Non-alcoholic Fatty Liver Disease* / diagnosis
  • Non-alcoholic Fatty Liver Disease* / pathology
  • Pentanoic Acids*
  • Tandem Mass Spectrometry


  • n-pentanoic acid
  • Biomarkers
  • Pentanoic Acids