NIH, National Cancer Institute, Division of Cancer Treatment and Diagnosis (DCTD) NIH - National Institutes of Health National Cancer Institute DCTD - Division of Cancer Treatment and Diagnosis

Evaporation of serum after long-term biobank storage: A chemical analysis of maternal serum from a large Danish pregnancy screening registry.

Author(s): Uldbjerg CS, Sørensen KM, Lindh CH, Rantakokko P, Hauser R, Juul A, Andersson AM, Bräuner EV

Publication: PLoS One, 2023, Vol. 18, Page e0293527

PubMed ID: 37883412 PubMed Review Paper? No

Purpose of Paper

This paper compared the concentration of sodium (Na+) and chloride (Cl-) in serum specimens that were collected from pregnant women and then stored at -20°C for 27-37 years. The number of specimens with Na+ or Cl- levels that were outside of the normal reference range were compared between serum specimens that were collected from pregnant women and then stored frozen for 27-37 years and serum specimens that were collected from non-pregnant women that were analyzed immediately.

Conclusion of Paper

A high percentage of the serum specimens collected from pregnant women had Na+ or Cl- concentrations outside of the normal range (38.9% and 43.6%, respectively), with the vast majority of the specimens in question above the normal range (106 of 107 for Na+ and 116 of 120 for Cl-). In contrast only 3.7% and 4.3% of specimens fell outside the normal range for Na+ and Cl- levels, respectively,  when fresh serum from non-pregnant women was analyzed; the specimens in question were predominantly below the normal range for Na+ and Cl-.  For all frozen storage durations evaluated using  serum collected from pregnant women, the variability in Na+ and Cl- levels was higher than normal biological variation. Importantly, Na+ and Cl- concentrations were not correlated with the duration of frozen storage and no consistent effect of specimen volume was observed.

Studies

  1. Study Purpose

    This paper compared the concentration of Na+ and Cl- in serum specimens that were stored at -20°C for 27-37 years in order to assess effects associated with evaporation. The number of specimens with Na+ or Cl- levels that were outside of the normal reference range were compared between serum collection from pregnant women that was stored frozen for 27-37 years and serum collected from non-pregnant women that was analyzed fresh.  This study used serum that was retrospectively collected from 275 pregnant women (14-22 weeks of gestation) between 1985 and 1995 (25 patients/per year). Serum was obtained from coagulated blood by centrifugation at 4°C and 3000 g (duration not specified) and stored at -20°C in screw top cryotubes for 27-37 years before analysis. Serum was thawed at room temperature for ≤2 h and mixed before quantification of Na and Ca using a Roche Cobas 6000 ion-selective electrode. Na+ and Cl- levels were compared to those in serum that was collected from 24,199 non-pregnant women; serum specimens were obtained by centrifugation at 3100 RPM for 10 min at 21˚C and stored for <24 hours in a climate chamber before analysis.

    Summary of Findings:

    A high percentage of serum specimens collected from pregnant women had Na+ or Cl- concentrations that were outside of the normal range (38.9% and 43.6%, respectively), with the vast majority of specimens in question above the normal range (106 of 107 for Na+ and 116 of 120 for Cl-). In contrast, only 3.7% and 4.3% of specimens fell outside the normal range for Na+ and Cl-, respectively, when serum from non-pregnant women were analyzed within 24 h of collection; the majority of these specimens fell below the normal range for Na+ and Cl-.  , The variability in Na+ and Cl- was higher than the normal biological variation for all of the frozen storage durations evaluated using serum collected from pregnant women. Importantly, the Na+ and Cl- concentrations in serum from pregnant women were not correlated with frozen storage duration, and no consistent effect of specimen volume was observed.

    Biospecimens
    Preservative Types
    • None (Fresh)
    • Frozen
    Diagnoses:
    • Not specified
    • Pregnant
    Platform:
    AnalyteTechnology Platform
    Electrolyte/Metal Ion selective electrode
    Pre-analytical Factors:
    ClassificationPre-analytical FactorValue(s)
    Preaquisition Diagnosis/ patient condition Pregnant
    Non-pregnant
    Storage Storage duration 27-37 years
    Biospecimen Aliquots and Components Aliquot size/volume Unspecified range of volumes < 2 mL

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