Estimating the long-term effects of storage at -70 degrees C on cholesterol, triglyceride, and HDL-cholesterol measurements in stored sera.

Author(s): Shih WJ, Bachorik PS, Haga JA, Myers GL, Stein EA

Publication: Clin Chem, 2000, Vol. 46, Page 351-64

PubMed ID: 10702522 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 up to 7 years storage of serum at -70 degrees C on measurement of cholesterol and triglycerides. Fasting serum from individuals on the American heart association step 1 diet was stored in polypropylene tubes. Except for specimens analyzed fresh and after 1 year, all specimens from a single individual were analyzed together.

   Summary of Findings:

   Total cholesterol levels were similar in specimens stored at -70 degrees C for 1 year and in fresh specimens, but HDL-cholesterol and triglycerides were slightly lower in specimens stored frozen for 1 year than in fresh specimens, showing average decreases of 0.009 and 0.018 g/L, respectively. In specimens frozen for at least 1 year, small average decreases in total cholesterol (-0.0370 g/L), HDL-cholesterol (-0.0068 g/L), and triglycerides (-0.0566 g/L) were observed when specimens were stored for 1 additional year. With longer storage, on average, total cholesterol declined by 0.071 g/L per year. The storage effect and storage duration were not correlated for triglycerides and HDL-cholesterol making a similar calculation of loss per year not possible. In general, additional storage led to decreased levels of HDL cholesterol, and additional storage decreased triglycerides for the first 4-5 years and then increased with additional storage.

   Biospecimens

   • Bodily Fluid - Serum
   • Bodily Fluid - Blood

   Preservative Types

   • Frozen
   • None (Fresh)

   Diagnoses:

   • Not specified
   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Lipid	Clinical chemistry/auto analyzer
   Steroid	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	0 years <1 year 1-2 years 2-3 years 3-4 years 4-5 years 5-6 years 6-7 years
   Preaquisition	Diagnosis/ patient condition	Moderately elevated total and low density lipoprotein cholesterol
   Biospecimen Acquisition	Time of biospecimen collection	Study start 12 month follow-up 30 month follow-up 36 month follow-up 42 month follow-up 48 month follow-up 54 month follow-up 60 month follow-up 66 month follow-up
   Biospecimen Preservation	Type of fixation/preservation	Frozen None (fresh)

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