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When hemolysis changes interpretation: decision-level shifts and reportability failures in routine coagulation
Özben Özden Işıklar1, Evin Kocatürk1
1Department of Medical Biochemistry, Faculty of Medicine, Eskişehir Osmangazi University, Eskişehir, Turkey.
Hemolysis is common in coagulation testing, yet generic acceptance or rejection rules may not reflect analyte-, decision-level, and reportability-specific effects. We assessed graded hemolysis across clinical decision strata on the Sysmex CS-5100. Residual citrated plasma was pooled into five decision strata for PT/INR, aPTT, Clauss fibrinogen, and D-dimer (≥20 specimens/pool), spiked with standardized hemolysate to final hemolysis levels of 0-5% (0, 0.5, 1, 2, 3, 4, 5%), and measured in five replicates. Hemolysis severity was characterized using CS-5100 sample-check HI/flags, XN-1000 cell-free hemoglobin, and Roche cobas c702 hemolysis index. Percent bias versus the matched non-hemolyzed baseline was evaluated against EFLM-derived desirable bias specifications and RCV-based allowable change limits. Hemolysis effects were analyte- and decision-level dependent. PT/INR showed overall limited effects, although selected confidence intervals crossed desirable bias limits; all PT results remained within RCV-based limits. aPTT showed a biphasic, stratum-dependent pattern, with prolongation in lower strata and shortening in prolonged strata. Fibrinogen showed positive bias, but progressive loss of reportability, with earlier 'No coagulation' in low-fibrinogen strata, was more clinically relevant. D-dimer showed modest, consistent negative bias, mainly exceeding desirable bias in the lowest stratum; no above-cutoff pool shifted below the 0.50 mg/L FEU deep vein thrombosis cutoff. Across all assays, reportable results remained within RCV-based limits. Hemolysis management should integrate analyte- and decision-level effects, numeric reportability, instrument-derived HI/flags, and clinical context rather than rely on a universal rejection rule.
Hemolysis is common in coagulation testing, yet generic acceptance or rejection rules may not reflect analyte-, decision-level, and reportability-specific effects. We assessed graded hemolysis across clinical decision strata on the Sysmex CS-5100. Residual citrated plasma was pooled into five decision strata for PT/INR, aPTT, Clauss fibrinogen, and D-dimer (≥20 specimens/pool), spiked with standardized hemolysate to final hemolysis levels of 0-5% (0, 0.5, 1, 2, 3, 4, 5%), and measured in five replicates. Hemolysis severity was characterized using CS-5100 sample-check HI/flags, XN-1000 cell-free hemoglobin, and Roche cobas c702 hemolysis index. Percent bias versus the matched non-hemolyzed baseline was evaluated against EFLM-derived desirable bias specifications and RCV-based allowable change limits. Hemolysis effects were analyte- and decision-level dependent. PT/INR showed overall limited effects, although selected confidence intervals crossed desirable bias limits; all PT results remained within RCV-based limits. aPTT showed a biphasic, stratum-dependent pattern, with prolongation in lower strata and shortening in prolonged strata. Fibrinogen showed positive bias, but progressive loss of reportability, with earlier 'No coagulation' in low-fibrinogen strata, was more clinically relevant. D-dimer showed modest, consistent negative bias, mainly exceeding desirable bias in the lowest stratum; no above-cutoff pool shifted below the 0.50 mg/L FEU deep vein thrombosis cutoff. Across all assays, reportable results remained within RCV-based limits. Hemolysis management should integrate analyte- and decision-level effects, numeric reportability, instrument-derived HI/flags, and clinical context rather than rely on a universal rejection rule.
