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pISSN 2950-9114 eISSN 2950-9122
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Lab Med Qual Assur 2024; 46(1): 60-65

Published online March 31, 2024


Copyright © Korean Association of External Quality Assessment Service.

Investigation of Effective Critical Value Thresholds for Laboratory Tests in Clinical Laboratories

Hanmil Jang1 , Jaehyeok Jang1 , Hyein Kang2 , John Hoon Rim1 , and Jong-Baeck Lim1

1Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul; 2Department of Laboratory Medicine, Keimyung University School of Medicine, Daegu, Korea

Correspondence to:John Hoon Rim
Department of Laboratory Medicine, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
Tel +82-2-2228-2437
E-mail johnhoon1@yuhs.ac

Received: September 28, 2023; Revised: December 15, 2023; Accepted: December 26, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


The establishment and prompt reporting of critical values to patient care providers is one of the crucial requirements of clinical laboratories. Each laboratory is expected to individually establish the thresholds of critical values and periodically update the lists. In this study, we attempted to investigate the status of critical value reporting (CVR) systems in Korean clinical laboratories and develop adequate guidelines based on comparative reviews examining expert consensus. In responses from 11 clinical laboratories, the number of test items with a critical value threshold was 9.4 on average (standard deviation=5.0). Some of the test items, especially ammonia, lactate, and carboxyhemoglobin, lacked critical value thresholds despite having been recommended by expert opinions and guidelines. The upper limit of critical value thresholds showed variability, with glucose showing the largest difference among laboratories (range, 450–700 mg/dL; coefficient of variation=14.7%). When evaluating the appropriateness of establishing critical value for a particular test, it is generally recommended to consider the “actionability” factors, which consist of effectiveness in decreasing mortality, availability of immediate response systems, and inclusion of the decision-making process in the institution’s critical pathway of standard patient care. As for the optimal value of individual thresholds, laboratory managers should review three quantitative markers: the ratio of CVR cases in total reported results, the ratio of confirmed CVR and responses by clinicians in total CVR cases, and the turnaround time of the tests assigned with critical value thresholds.

Keywords: Critical value report, Laboratory critical values, Laboratory management, Quality improvement

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