Automated assay for plasma D-lactate by enzymatic spectrophotometric analysis with sample blank correction.
BACKGROUND
D-lactate is essentially a product of bacterial metabolism, and its assessment in plasma has been mainly used to diagnose D-lactic acidosis in patients with short bowel syndrome. In the last few years, there has been growing interest in the use of subclinical elevations of D-lactate concentrations as a diagnostic tool in a variety of clinical conditions such as ischaemia, trauma or infection.


METHODS
An endpoint enzymatic spectrophotometric assay to measure plasma D-lactate with a sample blank correction was validated on our routine clinical chemistry analyser (Olympus AU640). An ultrafiltration procedure was used in samples with a high L-lactate dehydrogenase (L-LDH) activity in order to avoid underestimation of the D-lactate concentration, when a sample blank was processed.


RESULTS
The intra- and inter-assay imprecision were <5.1% and <13.3%, respectively and the mean recovery for the D-lactate assay was 95% (range 88-103%). Samples with L-LDH activity greater than 1500 IU/L required the use of ultrafiltration devices. Plasma D-lactate concentration in our 'non-diseased' paediatric population showed a non-Gaussian distribution--95th percentile equal to 19 micromol/L--and no difference based on gender or age was observed.


CONCLUSIONS
We have established an accurate, sensitive and precise routine assay for D-lactate measurement in plasma. The assay was used to formulate paediatric reference ranges and will be used to assist clinicians to evaluate 'D-lactate toxicity' in patients with a variety of conditions such as short bowel syndrome, small bowel transplantation and as an early marker of intestinal ischaemia.
Herrera
Daniel Juan
DJ
Department of Clinical Chemistry, Birmingham Children's Hospital, Steelhouse Lane, Birmingham B4 6NH, UK. daniel.herrera@bch.nhs.uk
Morris
Kevin
K
Johnston
Chris
C
Griffiths
Paul
P
D001681:Biological Assay; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D007773:Lactates / Q000097:blood*; D012016:Reference Values; D012778:Short Bowel Syndrome / Q000175:diagnosis; D013053:Spectrophotometry / Q000379:methods*
D007773:Lactates; D007770:L-Lactate Dehydrogenase