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Effects of Freezing and Thawing Procedures on Selected Clinical Chemistry Parameters in Plasma.

Author(s): Freiburghaus K, Leichtle AB, Nakas CT, Fiedler GM, Largiadèr CR

Publication: Biopreserv Biobank, 2020, Vol. , Page

PubMed ID: 32429745 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The study investigated the effects of freezing and thawing method on levels of 10 clinical chemistry analytes in lithium heparin plasma. Levels of all ten analyte were compared to those in specimens that were not frozen. Leftover routine lithium heparin plasma specimens stored at 4°C for <24 h were pooled. A total of twelve plasma pools, consisting of 6 specimens each, were created. Pools were split to create seven aliquots in cryotubes. One aliquot was analyzed immediately while two aliquots were snap-frozen in liquid nitrogen and stored at -80°C, two aliquots were placed in a cryobox at -80°C, and the last two aliquots were frozen in a controlled rate freezer (chilled to 8°C, frozen to -15°C at a rate of -3°C/min, frozen to 50°C at a rate of -5°C/min, and finally frozen to -140°C at a rate of -40°C/min). Three days after freezing, specimens were thawed either at room temperature for 30 min or in a 25°C water bath for 3 min and vortexed for 1 min. Levels of total calcium, potassium, sodium, alanine aminotransferase (ALAT), lactate dehydrogenase (LDH), lipase, uric acid, albumin, C-reactive protein (CRP), and total protein were measured using a Cobas 8000 analyzer.

   Summary of Findings:

   Although small differences in absolute values of analytes were observed among the different freezing methods, no statistically significant effects were observed. Similarly, nine of ten analytes only displayed minor differences when thawed at room temperature or in a water bath but LDH was significantly higher when thawed slowly at room temperature rather than quickly in a water bath (P= 1.07e^-5). Importantly, there was no interaction between freezing method and thawing method identified on LDH. When compared to baseline, significant differences in potassium (P= 0.002), sodium ( p = 0.045), LDH (P<0.001), lipase (P< 0.001), uric acid (P= 0.039), albumin (P= 0.022), and CRP (P< 0.001) were observed. Diagnostically unimportant but statistically relevant changes in potassium were observed between baseline and box-frozen or snap-frozen specimens, regardless of thaw method, and control-rate frozen when thawed at room temperature. Statistically relevant changes in sodium were observed between baseline and snap-frozen specimens regardless of thaw method and control-rate frozen when thawed at room temperature. Statistically relevant but diagnostically unimportant changes in LDH, CRP, and lipase were observed between all frozen specimens regardless of freezing and thawing method (P<0.001, all). Statistically relevant but diagnostically unimportant changes in uric acid were observed between baseline and box-frozen, regardless of thaw method, and snap-frozen when thawed at in a water bath. Albumin was significantly lower in control-rate frozen specimens thawed at room temperature than in baseline specimens (P=0.002).

   Biospecimens

   • Bodily Fluid - Plasma

   Preservative Types

   • None (Fresh)
   • Frozen

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Electrolyte/Metal	Clinical chemistry/auto analyzer
   Small molecule	Clinical chemistry/auto analyzer
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Preservation	Cooling or freezing method/ rate	Liquid nitrogen At -80 degrees C Multiple steps in controlled rate freezer
   Storage	Thaw temperature/condition	Room temperature for 30 min 25°C water bath for 3 min
   Biospecimen Preservation	Type of fixation/preservation	Frozen Snap frozen Refrigeration

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