Determination of d-lactate by enzymatic methods in biological fluids: study of interferences

• DOI: 10.1093/clinchem/43.6.1010
• Publication Date: 2020-01-23T06:03:57Z
• Authors: Ramon Martí; Encarna Varela; Rosa M Segura; José Alegre; José M Suriñach; Carles Pascual
• Keywords: 0301 basic medicine; Kinetics; 03 medical and health sciences; L-Lactate Dehydrogenase; Spectrophotometry; Humans; Pleura; Stereoisomerism; Lactic Acid; Hemofiltration; NAD; Body Fluids

Abstract Analysis of nondeproteinized samples with an enzymatic method to determine d-lactate indicated interferences. The presence of l-lactate dehydrogenase (LD) and l-lactate in the sample led to underestimation of d-lactate content when a sample blank was processed and overestimation when it was omitted. We proved that this interference is not due to lack of d-LD stereospecificity. Moreover, assessment of d-LD and l-LD KM for NAD+ allowed us to rule out the different affinities for this coenzyme as a cause of the interference. Our results underline the importance of deproteinizing samples for d-lactate analysis when enzymatic methods are used. The ultrafiltration procedure we propose is convenient and shows acceptable mean recovery (108%) and good imprecision (within-run CV = 4.2% and 3.0% for d-lactate at 31 and 107 μmol/L, respectively; between-run CVs were 7.3% at 49 μmol/L d-lactate and 3.1% at 115 μmol/L d-lactate).