Related Experiment Videos
The prolongation of the thrombotest clotting time in newborns
K Hamulyák1, P P Devilée, W Nieuwenhuizen
1Department of Biochemistry, Medical Faculty, University of Limburg, the Netherlands.
Insights
Human umbilical cord plasma often contains clotting inhibitors, potentially due to enhanced fibrinolytic activity. Thrombotest clotting assays may not accurately assess vitamin K-dependent factors in newborns.
Area of Science:
- Biochemistry
- Hematology
- Neonatal Medicine
Background:
- Human umbilical cord plasma frequently exhibits clotting inhibition.
- Vitamin K-dependent coagulation factors are crucial for hemostasis.
Purpose of the Study:
- To investigate the nature of clotting inhibition in human umbilical cord plasma.
- To evaluate the utility of Thrombotest assays for assessing coagulation factors in neonates.
Main Methods:
- Analysis of thrombotest dilution curves in 40 healthy term infant plasma samples.
- Correlation analysis between thrombotest clotting times and prothrombin levels.
- Sensitive enzyme immunoassays for fibrin and fibrinogen degradation products (FbDP/FgDP).
Main Results:
- Clotting inhibiting material was detected in 67% of samples.
- A moderate negative correlation (r = -0.46) was observed between thrombotest clotting times and prothrombin levels.
- Elevated levels of FbDP/FgDP, undetectable by conventional assays, were found in inhibited samples.
Conclusions:
- Thrombotest clotting assays have limited value for assessing vitamin K-dependent factors in umbilical cord plasma.
- Findings suggest enhanced in vivo fibrinolytic activity in neonatal circulation.
- Presence of fibrin and fibrinogen degradation products is a key indicator.
Abstract:
As judged from thrombotest dilution curves clotting inhibiting material was present in 67% of human umbilical cord plasma samples of healthy full term infants (n = 40). The correlation coefficient (r-value) between the thrombotest clotting times and the prothrombin levels was -0.46. Using sensitive enzyme immuno assays for fibrin degradation products (FbDP) and fibrinogen degradation products (FgDP), we found that no degradation products could be demonstrated in the non-inhibited group whereas small amounts of these products were present in the inhibited group. These small amounts were undetectable using conventional assays. The most striking finding was the presence of fibrin and fibrinogen degradation products. The prolongation of the thrombotest clotting time could be imitated by adding fibrinogen fragment X to umbilical cord plasma in which no clotting inhibiting material was present in the thrombotest dilution curve. We conclude that the thrombotest clotting is of limited value in the assessment of the vitamin K-dependent coagulation factors in umbilical cord plasma. As utmost care was taken to avoid proteolytic breakdown in vitro, our findings most likely reflect an enhanced fibrino(geno)lytic activity in umbilical cord plasma in vivo.