Objectives: Identification and quantification of hemolysis in serum or plasma samples is an important requirement in laboratory diagnostics; however, this is not always possible automatically, and visual sample inspection is not sufficiently accurate. We have planned this study to determine whether a commercially available urine dipstick with a hemoglobin-reactive pad could be used for this purpose. Materials and Methods: Sixty-five routine plasma samples, whose hemolysis index (HI) was previously determined on Roche Cobas 8000, were assayed with a commercial urine dipstick to obtain semi-quantitative data on plasma hemoglobin. Plasma was diluted 1:1000 in water to enter the dipstick’s range of hemoglobin measurement, and 10 µL of this dilution was applied to the hemoglobin pad. Results were visually interpreted within 60 s by comparing the pad color with that on the dipstick box label. Statistical Analysis: Semi-quantitative test results obtained with the urine dipstick were directly correlated with those of the same samples assayed on Roche Cobas 8000 using non-parametric Spearman’s correlation and agreement. Results: The sample size consisted of 40 non-hemolyzed (HI ≤0.3 g/L) and 25 hemolyzed (HI >0.3 g/L) plasma samples. Spearman’s correlation between Cobas HI and dipstick hemoglobin concentration was r = 0.96 (95% confidence interval, 0.93–0.97; P < 0.001). The concordance of hemolysis detection was 95.4%, with 1.00 sensitivity, 0.93 specificity, 1.00 negative predictive value, and 0.89 positive predictive value compared to the reference HI measurement on Cobas. The cumulative agreement between Cobas HI and the various plasma hemoglobin thresholds obtained with the dipstick was 75.4%. Conclusions: We have demonstrated here that plasma hemoglobin assessment with commercially available urine dipsticks may generate semi-quantitative test results accurate enough to influence decision-making regarding sample quality and its suitability for testing.
Accuracy of screening for hemolysis in plasma samples using a commercial urine dipstick
Pighi, Laura;Nitto, Simone De;Lippi, Giuseppe
2024-01-01
Abstract
Objectives: Identification and quantification of hemolysis in serum or plasma samples is an important requirement in laboratory diagnostics; however, this is not always possible automatically, and visual sample inspection is not sufficiently accurate. We have planned this study to determine whether a commercially available urine dipstick with a hemoglobin-reactive pad could be used for this purpose. Materials and Methods: Sixty-five routine plasma samples, whose hemolysis index (HI) was previously determined on Roche Cobas 8000, were assayed with a commercial urine dipstick to obtain semi-quantitative data on plasma hemoglobin. Plasma was diluted 1:1000 in water to enter the dipstick’s range of hemoglobin measurement, and 10 µL of this dilution was applied to the hemoglobin pad. Results were visually interpreted within 60 s by comparing the pad color with that on the dipstick box label. Statistical Analysis: Semi-quantitative test results obtained with the urine dipstick were directly correlated with those of the same samples assayed on Roche Cobas 8000 using non-parametric Spearman’s correlation and agreement. Results: The sample size consisted of 40 non-hemolyzed (HI ≤0.3 g/L) and 25 hemolyzed (HI >0.3 g/L) plasma samples. Spearman’s correlation between Cobas HI and dipstick hemoglobin concentration was r = 0.96 (95% confidence interval, 0.93–0.97; P < 0.001). The concordance of hemolysis detection was 95.4%, with 1.00 sensitivity, 0.93 specificity, 1.00 negative predictive value, and 0.89 positive predictive value compared to the reference HI measurement on Cobas. The cumulative agreement between Cobas HI and the various plasma hemoglobin thresholds obtained with the dipstick was 75.4%. Conclusions: We have demonstrated here that plasma hemoglobin assessment with commercially available urine dipsticks may generate semi-quantitative test results accurate enough to influence decision-making regarding sample quality and its suitability for testing.
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