Accurate measurement of extended half-life and unmodified factor VIII low levels with one-stage FVIII assays is dependent on the matrix of calibration curves.
Haemophilia
; 25(1): e19-e26, 2019 Jan.
Article
em En
| MEDLINE
| ID: mdl-30589148
ABSTRACT
INTRODUCTION:
The monitoring of factor VIII (FVIII) replacement therapy relies on the accurate measurement of FVIII activity over a large concentration range. However, unexplained overestimation of low FVIII levels has recently been reported with extended half-life recombinant FVIIIs.AIM:
The objective of this study was to confirm previous publications indicating that the reagents used to generate the calibration curves determine the accuracy of the measurement of low FVIII levels.METHODS:
We generated FVIII calibration curves with FVIII-deficient plasmas or a commercial diluent buffer. We then measured FVIII levels in FVIII-deficient plasma spiked with plasma FVIII, a full-length recombinant FVIII (Advate® , Shire, Brussels, Belgium) and two extended half-life recombinant FVIIIs (Elocta® , Swedish Orphan Biovitrum, Woluwe Saint-Lambert, Belgium and Afstyla® , CSL Behring, Mechelen, Belgium). FVIII levels were also analyzed in spiked samples prediluted two- and fourfold, either in diluent buffer or in FVIII-deficient plasma to evaluate parallelism.RESULTS:
Coagulation times of calibration curves generated with diluent buffer were longer than those with FVIII-deficient plasmas. This resulted in an overestimation of FVIII levels lower than 25 IU/dL in spiked samples and in detection of FVIII activity (≥1 IU/dL) in FVIII-deficient plasma. Predilution of samples with diluent buffer rather than with FVIII-deficient plasma also led to discordant results.CONCLUSION:
Our data confirm that the generation of calibration curves by dilution in FVIII-deficient plasma is crucial for the accurate measurement of low FVIII levels. When serial dilutions of samples are analyzed, predilution in FVIII-deficient plasma is required to respect the parallelism criteria. These methods should be more generally implemented for coagulation instruments.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Testes de Coagulação Sanguínea
/
Fator VIII
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Haemophilia
Assunto da revista:
HEMATOLOGIA
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Bélgica