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Long term stability of lactate in uncentrifuged sodium fluoride/potassium oxalate blood collection tubes.

Author(s): Stevic I, Bolsover J, Moore R, Bhayana V

Publication: Ann Clin Biochem, 2023, Vol. , Page 45632231213746

PubMed ID: 37903217 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared plasma lactate levels in matched aliquots of NaF/KOx blood that were stored at room temperature for 15 min to 2 h or 15 min to 48 h before centrifugation and analysis.  Additionally, effects associated time to arrival in the laboratory were retrospectively analyzed in 8,929 patient NaF/KOx blood specimens. Extra NaF/KOx blood from 15 patients (diagnosis not specified) were aliquoted into standard round bottom clear aliquot tubes, and matched aliquots were stored at room temperature for 0, 15, 30, 45, 60, 75, 90, or 120 min before centrifugation (details not provided) and analysis. To investigate the effects of longer processing delays, extra NaF/KOx blood from 10 patients (diagnosis not specified) were aliquoted into standard round bottom clear aliquot tubes and matched aliquots were stored at room temperature for 0, 2, 6, 12, 24, and 48 h before centrifugation (details not provided) and analysis. Lactate was quantified using the Roche L-Lactate colorimetric enzymatic assay on a Roche c702 instrument. Statistical significance was defined as P<0.05. The allowable performance limit was defined as ±0.5 mmol/L for specimens with ≤4 mmol/L lactate and <±12% for specimens with >4 mmol/L lactate in “accordance with the Accreditation Canada Diagnostics/Institute of Quality Management in Healthcare Canada and the Royal College of Pathologists of Australia”. The time to arrival at the laboratory was compared in NaF/KOx blood specimens from 8,929 patients (no diagnosis specified).

   Summary of Findings:

   Blood stored for 90 and 120 min had significantly higher mean levels of plasma lactate than blood stored for ≤15 min (3.1%, P<0.001 and 4.1%, P<0.01, respectively), but the changes were well below the allowable limit of ±0.5 mmol/L (0.05 mmol/L and 0.06 mmol/L, respectively). In a second experiment, plasma lactate levels were comparable to baseline (stored ≤ 15 min) when blood was stored for 2 h at room temperature, but mean plasma lactate levels were significantly higher than baseline when blood was stored for 6 (+4.7%, P<0.05), 12 (+8.0%, P<0.05), 24 (+6.8%, P<0.05) and 48 (+9.8%, P<0.05) h before centrifugation and analysis; none of the changes in lactate levels exceeded the limit of acceptability.  Of the 8,929 NaF/KOx blood specimens analyzed in the laboratory over a 6 month period, 6,152 (69%) were received in the laboratory within the required 15 min, 1,124 (13%) were received after 16 to ≤ 30 min,  522 (6%) after 31 to ≤45 min,  306 (3%) after 46 to ≤60 min, 230 (3%) after 61 to ≤75 min, 180 (2%) after 76 to ≤90 min, 194 (2%) after 91 to ≤120 min, and 221 (2%) after more than 120 min.  

   Biospecimens

   • Bodily Fluid - Plasma
   • Bodily Fluid - Blood

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Small molecule	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Time at room temperature	≤15 min 30 min 45 min 60 min 75 min 90 min 120 min 2 h 6 h 12 h 24 h 48 h

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