Lactate Measured in Diluted and Undiluted Whole Blood and Plasma: Comparison of Methods and Effect of Hematocrit

Abstract

We evaluated a new analyzer that measures lactate in undiluted whole blood by direct (or undiluted) amperometry [Nova Stat Profile 7 Analyzer (SP7); Nova Biomedical, Waltham, MA] by comparing it with two other analyzers, one for measuring lactate in whole blood by indirect (or diluted) amperometry [Model 2300; Yellow Springs Instrument Co. (YSI), Yellow Springs, OH] and another for measuring lactate in plasma by enzymatic colorimetry (aca; Du Pont Co., Wilmington, DE). All between-method comparisons of the three methods showed that the results for plasma were comparable (Sy/x = 0.24-0.33 mmol/L). Within-method comparisons by the YSI differed substantially between plasma and whole blood (Sy/x = 0.48 mmol/L), but within-method comparisons by the SP7 produced better agreement between plasma and whole blood (Sy/x = 0.18 mmol/L). The difference between whole blood and plasma by YSI is related to hematocrit, with the greatest differences noted for samples with the highest hematocrit. Serum lactate measured by SP7 had between-day imprecision (CV) ranging from 12% at 0.5 mmol/L to 4.2% at 3.7 mmol/L, showed a linear standard curve to at least 11.5 mmol/L, and was independent of hematocrit. There was a mean bias of approximately 0.4 mmol/L for results in the reference range for both plasma and whole blood by SP7 compared with plasma results by either aca or YSI.

Assessment of a Point-of-Care Lactate Monitor in Emergency Admissions of Adult Horses to a Referral Hospital

“…27,28 This is particularly appropriate here because, although the blood gas analyzer is well accepted as an accurate clinical instrument, it is not a reference technique for lactate measurement. 17,26 An increased hematocrit has been previously identified as a confounder when measuring lactate concentration in horses on this POC monitor. 20 Large differences were recorded between the POC monitor and reference technique when lactate concentration was measured in whole blood in horses with PCV .53%.…”

“…This technique currently is considered a standard clinical technique for lactate measurement. 17,26 Lactate concentration also was measured with a hand-held lactate monitor. d Whole blood samples (Accutrend whole blood [AWB]) were measured with the venous blood gas sample immediately after blood gas analysis.…”

Technical Performance of Lactate Biosensors and a Test-Strip Device during Labour

“…Within the concentration range of 3 mmol / L the Bias (syst) amounts to 0.24 mmol / L and the lower delimitation of the confi dence interval is situated at 0.50 mmol / L. These negative diff erences increase with rising lactate concentration: At a lactate value of 6 mmol / L the Bias (syst) already amounts to 0.48 mmol / L, and the 95 % confi dence interval is downward limited by the value 0.75 mmol / L. ments of fetal lactate as a direct metabolite of anaerobic glycolysis within seconds in the labour room. Due to the continuous glycolysis, in vitro lactate depends on the metabolic activity of the erythrocytes [24,25] . Therefore, the clinical consequence of the various methods and mediums being applied for lactate measurement is that no standardised lactate reference values are currently available [17, 19 -23] .…”

“…The duration of tonometry which ranged up to 40 min may have caused a certain degree of hemolysis and vaporisation [25] . Still, this cannot properly explain why the repetitive measurements from identical tonometered samples showed such clinically relevant diff erences.…”

Plasmatic l‐lactate in pet rabbits: association with morbidity and mortality at 14 days

“…Plasma samples were stored refrigerated for a maximum of 36 h. The PLLC was determined by an enzymatic colorimetric method via lactate oxidase and peroxidase ( l ‐Lactate Trinder Liquid; BEN – Biochemical Enterprise s.r.l., Milan, Italy), and an end‐point reaction method using wavelengths of 545 nm at 37°C measured by a commercial spectrophotometer (BSE‐120; Mindray, Shenzhen, China). Both techniques had been previously described and validated for human plasma with linear results up to 13.3 mmol/L and an analytic threshold at 0.16 mmol/L in human plasma. Samples exceeding the upper limit of linearity were diluted with distilled water and repeated.…”