kjlm The Korean Journal of Laboratory Medicine Korean J Leg Med 2383-5702 2383-5710 The Korean Society for Legal Medicine 10.7580/kjlm.2020.44.1.17 kjlm-44-17 Original Article Usefulness of Mast Cell Tryptase Analysis for Postmortem Diagnosis of Anaphylactic Shock ParkJong-Pil 1 KooBon Young 2 LeeNak-Won 3 Department of Forensic Medicine, Yonsei University College of Medicine, Seoul, Korea Division of Forensic Medicine, National Forensic Service Daegu Institute, Chilgok, Korea Division of Forensic Medicine, National Forensic Service Daejeon Institute, Daejeon, Korea Correspondence to Jong-Pil Park Department of Forensic Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea Tel: +82-2-2228-2482 Fax: +82-2-362-0860 E-mail: parkjp@yuhs.ac 12020 812020 441 1723 30012020 12022020 21022020 Copyright © 2020 The Korean Society for Legal Medicine 2020 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. Abstract

Anaphylactic shock (AS) is a systemic and life-threatening type I hypersensitivity reaction and is often encountered at an autopsy. However, postmortem diagnosis of AS can be difficult due to non-specific autopsy findings. Clinically, the analysis of serum mast cell tryptase (MCT) is well known as a useful ancillary test for the diagnosis of AS. However, in order to apply this test to forensic autopsy, it is necessary to confirm its usefulness due to postmortem changes. We carried out serum MCT analysis in 299 autopsy cases including nine AS cases at National Forensic Service from January 2013 to May 2015 and analyzed the difference according to the cause of death and degree of postmortem change. As a result, the MCT level in AS was significantly increased compared to others, and the appropriate cutoff value for postmortem diagnosis of AS was 63.0 μg/L (sensitivity 88.9%, specificity 98.6%). Conclusively, serum MCT analysis is a useful test for postmortem diagnosis of AS and seems to be more appropriate for screening rather than confirmation.

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Comparison of mast cell tryptase level among groups according to cause of death. AS, anaphylactic shock; IHD, ischemic heart disease; SIDS, sudden infant death syndrome; AFE, amniotic fluid embolism.

Receiver operating characteristic (ROC) curve for mast cell tryptase levels to diagnose anaphylactic shock.

Anaphylactic shock cases

Case No. Sex Age (yr) PMI (hr) Mast cell tryptase (μg/L) K+ (mEq/L) Allergen
Peripheral blood Heart blood
1 M 65 72 77.5 - >15 Bee sting
2 M 56 40 232 - - Ranitidine
3 M 2 78 100.4 56. - Cefotaxime
4 F 68 40 272.4 - 11.6 Cefradine
5 F 70 45 208.5 - 13.7 Ceftriaxone
6 F 48 18 9.8 4.1 8.9 Bee sting
7 M 57 66 191.9 141.5 >15 Bee sting
8 F 56 36 294.5 272.3 13.1 Bee sting
9 M 58 46 88.8 73.8 14.4 Bee sting

PMI, postmortem interval.

Comparison between peripheral blood and heart blood on the mast cell tryptase concentration

P/H No. (%)
<0.25 5 (3.8)
0.25-0.5 14 (10.5)
0.5-1.0 29 (21.8)
1.0-2.0 61 (45.9)
2.0-4.0 21 (15.8)
>4.0 3 (2.2)
Total 133

P/H, ratio of peripheral blood and heart blood.

Comparison of mast cell tryptase level among groups according to COD

COD No. Mean±SD (μg/L) Median (IQR) (μg/L) Range (μg/L) P-value a)
AS 9 164.0±98.2 191.9 (169.0) 9.8-294.5
IHD 76 10.3±18.4 6.4 (4.7) 0.1-146.7
Head injury 22 7.9±5.7 6.6 (4.5) 1.0-27.2
SIDS 9 2.9±2.7 2.0 (3.7) 0.0-8.8 <0.001
Asthma 3 4.7±1.9 4.1 3.1-6.8
AFE 2 11.7±10.3 11.7 4.4-18.9
Control 178 10.4±20.5 5.9 (7.5) 0.0-233.0

COD, cause of death; SD, standard deviation; IQR, interquartile range; AS, anaphylactic shock; IHD, ischemic heart disease; SIDS, sudden infant death syndrome; AFE, amniotic fluid embolism.

P-values were determined with use of the Kruskal-Walis test.

Analysis of variables affecting on postmortem mast cell tryptase concentration

Variable No. Value P-value
Sex   Median (IQR) (μg/L)  
 Male 208 6.15 (6.20) 0.796
 Female 82 5.85 (6.53)  
    Correlation coefficient  
Age 289 0.102 0.085
PMI 266 0.094 0.127
K+ 171 0.158 0.039

P-value for sex was determined with use of the Mann-Whitney U test. P-values for age, PMI, and K+ were determined with use of Spearman correlation.

IQR, interquartile range; PMI, postmortem interval.

Sensitivity and specificity of postmortem mast cell tryptase anlysis for anaphylactic shock diagnosis

Mast cell tryptase level (μg/L) Sensitivity Specificity
>11.4 0.889 0.817
>20 0.889 0.931
>30 0.889 0.972
>40 0.889 0.976
>50 0.889 0.979
>60 0.889 0.983
>70 0.889 0.986
>80 0.778 0.986
>90 0.667 0.990
>100 0.667 0.993

False-positive cases

Case No. Sex Age (yr) PMI (hr) Mast cell tryptase (μg/L) K+ (mEq/L) Cause of death
Peripheral blood Heart blood
1 F 53 41 64.6 - 12.2 Ischemic heart disease
2 F 57 54 82.7 24.8 >15 Nontraumatic ICH
3 M 47 38 99.7 73.8 >15 Drowning
4 M 50 25 146.7 4.1 9.0 Ischemic heart diease
5 F 32 30 233 - 10.2 Drowning
6 M 74 39 27.2 71.3 13.3 Head injury
7 M 84 43 5.9 94.9 >15 Head injury
8 M 51 50 4 108.7 >15 Nontraumatic ICH
9 M 33 - 9 262.9 - Multiple injury d/t fall

PMI, postmortem interval; ICH, intracerebral hemorrhage.