ABSTRACT
OBJECTIVES: To determine the impact of residual platelets on dilute Russell's viper venom time (DRVVT) assay in frozen-thawed plasma submitted for lupus anticoagulant (LAC) testing. METHODS: We measured platelet counts in frozen-thawed samples submitted for LAC testing and evaluated the association between platelet count and the DRVVT screening time and ratios. We also spiked platelets into a LAC-positive sample to observe the effect on the DRVVT. RESULTS: Progressive increase in platelet count resulted in a statistically significant shortening of the DRVVT assay results on plasma after 1 freeze-thaw cycle. A similar effect was noted on the LAC-positive sample. CONCLUSIONS: Residual platelets in plasma samples result in shortening of DRVVT assay after 1 freeze-thaw cycle. This may result in a false-negative LAC test result.
