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pISSN 2950-9114 eISSN 2950-9122
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Brief Communication

Lab Med Qual Assur 2021; 43(4): 208-213

Published online December 31, 2021


Copyright © Korean Association of External Quality Assessment Service.

Measurement of Plasma Free Hemoglobin Using Hemolysis Index and Bilirubin Interference

Hanmil Jang1 , Yonggeun Cho2 , John Hoon Rim1 , Hyein Kang1 , Sang-Guk Lee1 , and Jong-Baeck Lim1

1Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul; 2Department of Laboratory Medicine, Hallim University Sacred Heart Hospital, Anyang, Korea

Correspondence to:Sang-Guk Lee
Department of Laboratory Medicine, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
Tel +82-2-2228-2455
E-mail comforter6@yuhs.ac

Received: June 8, 2021; Revised: August 25, 2021; Accepted: September 9, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Plasma hemoglobin (pHb) is measured when hemolysis is suspected as a result of biochemical, immunological, and mechanical conditions. In this study, we evaluated the clinical feasibility of the hemolysis index (H-index) for pHb measurement using automated chemistry analyzers. A total of 176 plasma samples were analyzed for pHb in the Severance Hospital using a Lambda 365 UV/Vis spectrophotometer (PerkinElmer, USA) and Fairbanks method 2. The remnant samples after pHb measurement were then analyzed for total bilirubin, and H-indices were determined using the automated Atellica CH930 system (Siemens, Germany) and Cobas c702 system (Roche, USA). The equivalence and correlation among the methods were evaluated using Passing-Bablok regression analysis and Spearman’s correlation analysis. All the methods showed high correlations with each other. However, the H-indices showed a negative constant bias compared to the Fairbanks method 2. When a cut-off value of 33.2 mg/dL was applied for diagnosis of hemolysis, 13 samples were determined positive by Fairbanks method 2 but negative by H-indices. These discordant results occurred mostly among samples with total bilirubin levels higher than 3 mg/dL (12 out of 13 samples). The correlation between total bilirubin and pHb measured by Fairbanks method 2 showed the largest correlation coefficient (R =0.347) and slope. These results suggest that the pHb measured by Fairbanks method 2 is more prone to bilirubin interference. In summary, our results suggest that H-indices from both automated chemistry analyzers possess excellent clinical feasibility for pHb measurements and have minimum total bilirubin interference compared to traditional measurement via Fairbanks method 2.

Keywords: Plasma hemoglobin, Hemolysis index, Spectrophotometry

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