Effects of repeated freeze-thaw cycles on concentrations of cholesterol, micronutrients, and hormones in human plasma and serum.

Author(s): Comstock GW, Burke AE, Norkus EP, Gordon GB, Hoffman SC, Helzlsouer KJ

Publication: Clin Chem, 2001, Vol. 47, Page 139-42

PubMed ID: 11148194 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of freeze-thaw cycling on levels of 14 hormones and 10 micronutrients in plasma and serum. All handling was performed on ice water and, for ascorbic acid, under dim light. For each cycle, specimens were thawed in cold water and stored at room temperature for 30 min before being refrozen at -70 degrees C. After freeze-thaw cycling, specimens were shipped on dry ice to different laboratories for analysis.

   Summary of Findings:

   Levels of each analyte changed by <4% with each freeze-thaw cycle. Three freeze-thaw cycles decreased estrone and estradiol, and increased testosterone in plasma and serum. Three freeze-thaw cycles increased SHBG in plasma and decreased SHBG in serum. All of these changes were less than the assay CV, and no other tested analytes were affected. Additional freeze-thaw cycles led to changes in other analytes, but the authors report that the changes were not large enough to be meaningful. Generally, freeze-thaw effects were smaller in plasma than serum.

   Biospecimens

   • Bodily Fluid - Serum
   • Bodily Fluid - Plasma

   Preservative Types

   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Steroid	Enzyme assay
   Steroid	Radioimmunoassay
   Glycoprotein	Radioimmunoassay
   Small molecule	HPLC
   Small molecule	Colorimetric assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Freeze/thaw cycling	1 cycle 2 cycles 3 cycles 4 cycles 6 cycles 10 cycles
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Serum

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