Fully automatic d-lactate assay using a modified commercially available method

Abstract

Intestinal infarction is the fast-evolving endpoint of impaired blood perfusion to an intestinal segment which may have fatal outcome. Early diagnosis and treatment within 6 h reduce mortality. Currently, d-lactate is a promising biomarker, however, not available in the acute clinical setting. The aim of this study is implementation of d-lactate analysis in a routine clinical setting. We used a spectrophotometric method, based on enzymatic oxidation of d-lactate by d-lactate dehydrogenase (D-LDH) coupled to the reduction of nicotinamide-adenine dinucleotide (NAD⁺). The amount of NADH formed in this reaction is equivalent to d-lactate. The primary concern in this method is interfering NADH formed by oxidation of l-lactate by l-lactate dehydrogenase (L-LDH). A commercially available kit for d-lactate measurement was implemented on our existing automated routine laboratory equipment including pH-inactivation of L-LDH. Our setup fulfilled clinical quality goals. We were able to measure d-lactate with an acceptable performance of the analysis and a short turn-around time. The method can be used to distinguish between the expected cut-off for intestinal ischemia around 0.3 mM and the upper reference limit of 0.05 mM. With a turnaround time of just 9 min, the analysis has potential as a readily available detection of circulating d-lactate for early diagnosis of intestinal ischemia.

Keywords:

• Intestines
• ischemia
• d-lactate dehydrogenase
• lactate dehydrogenases
• biomarkers
• early diagnosis
• infarction
• fatal outcome

Acknowledgments

The authors wish to thank Erland J. Erlandsen for providing support and the initial setup for the Roche Modular method as well as Lisbeth Søndergaard (Roche Diagnostics A/S) for support in adapting the setup for Cobas 8000. Furthermore, the authors acknowledge the excellent technical assistance supplied by Kirsten Kolind and Jane Syndergaard Pedersen.

Disclosure statement

The authors declare no conflict of interest.