Testing for lupus anticoagulants--fresh or frozen?
Author(s): Froom P, Barak M
Publication: Clin Chem Lab Med, 2012, Vol. 50, Page 1607-9
PubMed ID: 22962221 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine the effects of a single freeze-thaw cycle on normalized diluted Russel's viper venom test (dRVVT) and silica clotting time (SCT) ratios in plasma from patients with elevated dRVVT.
Conclusion of Paper
After frozen storage at -80 degrees C and thawing, 13 of 14 specimens had reduced dRVVT and SCT ratios compared to levels in fresh specimens. For 6 specimens, the decrease in dRVVT ratios resulted in missclassification as normal, but the decrease in SCT ratios did not cause missclassification of any specimens.
Studies
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Study Purpose
The purpose of this study was to determine the effects of a single freeze-thaw cycle on normalized dRVVT and SCT ratios in plasma from patients with elevated dRVVT. Fresh specimens were selected for this study based on having a normalized dRVVT ratio of >1.36. After initial testing, plasma was stored frozen at -80 degrees C for 16-75 days, thawed at 37 degrees C for less than 15 min, mixed and assayed within 1 h.
Summary of Findings:
After frozen storage at -80 degrees C and thawing, 13 of 14 specimens had reduced dRVVT and SCT ratios compared to levels in fresh specimens (p<0.0001, both). For 6 specimens, the decrease in dRVVT ratios resulted in missclassification as normal, but the decrease in SCT ratios did not cause missclassification of any specimens.
Biospecimens
Preservative Types
- None (Fresh)
- Frozen
Diagnoses:
- Lupus
Platform:
Analyte Technology Platform Morphology Hematology/ auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Freeze/thaw cycling 0 cycles
1 cycle
Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)