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The relevance of developmental hemostasis to hemorrhagic disorders of newborns
1Department of Hamilton Civic Hospitals Research Centre, ON.
Insights
The infant hemostatic system differs significantly from adults, with unique coagulation and fibrinolytic profiles. While generally effective, infants face higher bleeding risks with hemostatic defects, necessitating awareness of specific neonatal bleeding disorders.
Area of Science:
- Pediatric Hematology
- Hemostasis and Thrombosis
- Neonatal Physiology
Background:
- The hemostatic system is dynamic and age-dependent, with distinct protein concentrations in fetuses and infants compared to adults.
- Components of the hemostatic system are synthesized early in fetal life and do not transfer across the placenta.
Purpose of the Study:
- To detail the age-dependent characteristics of the hemostatic system in infants and children.
- To outline physiological reference ranges for hemostatic proteins in young individuals.
- To describe common congenital and acquired bleeding disorders in newborns and their management.
Main Methods:
- Review of physiological reference ranges for hemostasis in premature infants, full-term infants, and children (ages 1-16).
- Analysis of plasma concentrations of coagulation and fibrinolytic factors at birth.
- Description of clinical presentations and treatment guidelines for neonatal bleeding disorders.
Main Results:
- Infants exhibit decreased vitamin K-dependent and contact factors, but increased fibrinogen, FV, FVIII, and FXIII at birth.
- Neonatal fibrinolytic system shows decreased plasminogen with increased tissue plasminogen activator and plasminogen activator inhibitor.
- Healthy infants are generally protected from spontaneous bleeding, but are vulnerable to complications with hemostatic defects.
Conclusions:
- The neonatal hemostatic system is uniquely adapted but predisposed to bleeding complications in the presence of defects.
- Congenital bleeding disorders often manifest at birth, while acquired causes like DIC, vitamin K deficiency, and liver disease are common.
- Understanding these age-specific hemostatic differences is crucial for diagnosing and managing bleeding in neonates.
Abstract:
The hemostatic system is a dynamic evolving process that is age-dependent. Components of the hemostatic system are synthesized in early fetal life and do not cross the placenta from mother to fetus. However, plasma concentrations of proteins involved in hemostasis significantly differ from adults. Physiological reference ranges are available for premature infants, full-term infants and children from ages 1 to 16 years. In the coagulation system, plasma concentrations of the vitamin K-dependent and contact factors are decreased at birth, whereas other factors such as fibrinogen, FV, FVIII, and FXIII are similar or increased compared with adults at birth. In the fibrinolytic system, plasma concentrations of plasminogen are decreased at birth, whereas tissue plasminogen activator and plasminogen activator inhibitor are increased. Clinically, the hemostatic system of the young is effective and healthy infants do not suffer from spontaneous hemorrhagic complications. However, infants are more vulnerable, compared with older patients, for bleeding in the presence of either congenital or acquired haemostatic defects. Severe congenital bleeding disorders, although rare, frequently present in the newborn period. The most common acquired causes of bleeding newborns include disseminated intravascular coagulation, vitamin K deficiency, and liver disease. A description of these disorders and treatment guidelines are provided.