The "normal" factor VIII concentration in plasma.
Thromb Res
; 126(2): 119-23, 2010 Aug.
Article
em En
| MEDLINE
| ID: mdl-20451961
ABSTRACT
INTRODUCTION:
The quantitation of factor (F)VIII by activity-based assays is influenced by the method, procedure, the quality and properties of reagents used and concentrations of other plasma proteins, including von Willebrand factor (VWF).OBJECTIVE:
To compare FVIII concentrations measured by activity-based assays with those obtained by an immunoassay and to establish the influence of plasma dilution on the FVIII clotting activity (FVIIIc).METHODS:
The APTT, a chromogenic assay (Coatest) and two in-house immunoassays were used. Albumin-free recombinant FVIII was used as the calibrator in all assays.RESULTS:
For a group of 44 healthy individuals (HI), the mean value observed for FVIII antigen (FVIIIag; 1.22+/-0.56 nM; S.D.) is substantially higher than that for FVIIIc (0.65+/-0.29 nM) and the chromogenic assay (FVIIIch; 0.50+/-0.23 nM). A positive correlation between FVIIIag and VWFag with R(2)=0.20 was observed. Since plasma VWF has an inhibitory effect on FVIIIc, we evaluated the influence of plasma dilutions on FVIIIc in HI (n=105). At a 4-fold dilution, estimates of FVIIIc by clotting assay were much lower than FVIIIag (0.77+/-0.31 vs. 1.14+/-0.48 nM). At 10- and 25-fold dilutions, the estimated FVIIIc increased to 0.87+/-0.36 and 0.94+/-0.44 nM, respectively.CONCLUSIONS:
1) In plasma, FVIIIag is higher than FVIIIc and FVIIIch; and 2) Real FVIII concentrations in plasma can be estimated by measuring FVIIIag.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tempo de Tromboplastina Parcial
/
Fator VIII
/
Imunoensaio
Limite:
Adult
/
Female
/
Humans
/
Male
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article