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Review
. 2022 Apr;10(4):e578.
doi: 10.1002/iid3.578. Epub 2021 Dec 13.

Estimating the within-subject (CVI ) and between-subject (CVG ) biological variation of serum tryptase

Birthe R Skarbø  1 , Erik W Vinnes  1 , Tore Wentzel-Larsen  2   3   4 , Marit S Sylte  1 , Torunn O Apelseth  5   6   7
Affiliations
Review

Estimating the within-subject (CVI ) and between-subject (CVG ) biological variation of serum tryptase

Birthe R Skarbø et al. Immun Inflamm Dis. 2022 Apr.

Abstract

Background: Tryptase is used as a biomarker to support the diagnosis of anaphylaxis and hematologic diseases. In the event of a mast cell activation during anaphylaxis, a temporary increase in the concentration of tryptase may be seen. On the basis of clinical studies, an increase of 2 µg/L + 20% from basis level has been proposed as significant. To evaluate the increase in tryptase levels, the within-subject (CVI ) and between-subject (CVG ) biological variations should be known. This study was conducted to estimate the biological variation of tryptase and to identify the reference change value (RCV).

Methods: Blood samples were collected from healthy volunteers once a week consecutively over a 10-week period. Tryptase was measured by the use of a fluoroenzyme immunoassay (ImmunoCAPTM ; Thermo Fisher Scientific), and linear mixed-effects models were used to calculate the biological variation and RCV for both nontransformed and log-transformed tryptase.

Results: Fourteen presumably healthy young adults (six males and eight females, age 23-35 years) were included. The CVI was 5.6% and the CVG was 31.5% (nontransformed data). Log-transformed data showed similar results. The analytical variation (CVA ) was 6.3% and the RCV was 23.5%.

Conclusions: Young healthy adults without ongoing allergic reactions show low within-subject biological variation. Higher biological variation was observed between subjects.

Keywords: biological variation; reference change value; tryptase.

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Conflict of interest statement

The authors declare that there are no conflict of interests.

Figures

Figure 1
Figure 1
Biological variation of tryptase (µg/L) for each participant (n = 14). Participants 1–6 were male and 7–14 were female. Data points depict the mean values of the duplicates (n = 2) for each sample. The gray box represents the 25% and 75% percentiles, whiskers show range (min–max), and the median value is shown by the horizontal line
See this image and copyright information in PMC

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