The effect of storage time and freeze-thaw cycles on the stability of serum samples.
Author(s): Cuhadar S, Koseoglu M, Atay A, Dirican A
Publication: Biochem Med (Zagreb), 2013, Vol. 23, Page 70-7
PubMed ID: 23457767 PubMed Review Paper? No
Purpose of Paper
Conclusion of Paper
Studies
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Study Purpose
The purpose of this study was to determine the effects of up to 10 freeze-thaw cycles on the levels of 17 clinical chemistry analytes in serum from out-patients. Specimens were thawed at room temperature for 1 h before assay or refreezing and thawing the following day. Due to multiple testing, statistical significance was defined as p<0.005 compared to fresh specimens.
Summary of Findings:
After a single freeze-thaw cycle, total bilirubin and total protein levels were lower than in fresh specimens (p<0.001 and p=0.004, respectively). UA was higher after 2 freeze-thaw cycles than in fresh specimens (p=0.001). Further, BUN and calcium were stable for up to 3 freeze-thaw cycles, LD was stable for up to 5 freeze-thaw cycles, and albumin was stable for up to 7 freeze-thaw cycles. While levels of triglycerides increased and creatinine kinase (CK) decreased after 6 and 8 freeze-thaw cycles, respectively, the changes were clinically irrelevant. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), cholesterol, glucose, creatinine, direct bilirubin, and high density lipoprotein (HDL) cholesterol levels were unaffected by up to 10 free-thaw cycles.
Biospecimens
Preservative Types
- Frozen
- None (Fresh)
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Carbohydrate Clinical chemistry/auto analyzer Electrolyte/Metal Clinical chemistry/auto analyzer Lipid Clinical chemistry/auto analyzer Protein Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Steroid Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Freeze/thaw cycling 0 cycles
1 cycle
2 cycles
3 cycles
4 cycles
5 cycles
6 cycles
7 cycles
8 cycles
9 cycles
10 cycles
Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)
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Study Purpose
The purpose of this study was to determine the effects of up to 3 months of storage at -20 degrees C on the levels of 17 clinical chemistry analytes in serum from out-patients. Due to multiple testing, statistical significance was defined as p<0.013 compared to fresh specimens.
Summary of Findings:
Compared to fresh serum, serum stored for 3 months at -20 degrees C had statistically and clinically significant elevations in total protein and BUN levels. Albumin levels were non-significantly higher after 2 months at -20 degrees C but significantly lower after 3 months at -20 degrees C (p=0.001). While statistically significant decreases in ALT, AST, CK, GGT, and LD, and increases in UA were observed after storage at -20 degrees C compared to fresh specimens, the variations did not exceed the maximum desirable bias and were considered clinically irrelevant. Changes in creatinine, calcium, and BUN levels after storage at -20 degrees C compared to fresh specimens exceeded the maximum desirable variability but did not reach statistical significance.
Biospecimens
Preservative Types
- Frozen
- None (Fresh)
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Carbohydrate Clinical chemistry/auto analyzer Electrolyte/Metal Clinical chemistry/auto analyzer Lipid Clinical chemistry/auto analyzer Protein Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Steroid Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)
Storage Storage duration 0 months
1 month
2 months
3 months