Developmental Hemostasis: Relevance to Hemostatic Problems During Childhood

Abstract

Congenital and acquired hemostatic disorders present during childhood. An accurate diagnosis is critically important in order to implement optimal therapy. Over the last century, several investigators have measured plasma concentrations of hemostatic components in newborns and compared the results to adult values. Clinically significant differences exist for many hemostatic components. Recently, three large studies in more than 400 healthy children have provided reference ranges for hemostatic components throughout childhood. Together, these studies provide insight into the regulation of coagulation and fibrinolysis in children in physiologic and pathologic states. Some examples of the influence of age on hemostasis are: (1) the diagnosis of some congenital factor deficiencies, based on plasma levels, can be difficult due to physiologically low values; (2) despite very low levels of many inhibitors of hemostasis, thrombotic complications are rare; (3) the interaction of anti-coagulants and thrombolytic agents is profoundly influenced by the relative immaturity of hemostasis at birth; and (4) in contrast to the risk of thrombosis, healthy infants are at risk for vitamin K deficiency bleeding due to poor transport of vitamin K across the placenta and plasma concentrations of the vitamin K dependent proteins of less than 50% of adults values. The following review discusses the age dependency of hemostasis during childhood and the effect of the physiologically immature system on the diagnosis and treatment of hemostatic disorders.

Age-associated developmental changes in the activated partial thromboplastin time (APTT) and causes of prolonged APTT values in healthy Chinese children

“…The prolonged APTT values in neonates could be explained by markedly decreased plasma concentrations of the vitamin K-dependent factors (1,8,34) and contact factors, and partially by insufficient ratios of plasma to citrate caused by higher hematocrits (35). APTT values were also markedly prolonged in infants aged 1-6 months, which could be due to the hemostatic system of infants -6 months of age not being fully mature (6,7).…”

Determination of Pediatric Reference Intervals for Three Coagulation Tests in Widespread Use for City of Kayseri Population

“…Sonuçlarımız rehberliğinde koagulasyon laboratuvarlarının yetişkinlere ait referans değerlerini kullanmak yerine, çocuklar için kendi oluşturdukları yaşa ve cinsiyete bağlı referans aralıklarını kullanmalarının daha uygun olacağı düşüncesindeyiz. [8,11]. Bir toplumdaki etnik kökenlere bağlı olarak da koagulasyon parametrelerinin referans aralıklarında bazı farklılıklar bulunabilmektedir.…”

“…Bu nedenle yeni teknolojiler ve aletler kullanılarak daha kabul edilebilir ve kapsamlı bilgilerin oluşturulması acil ve önemlidir [1]. Çocukluk çağında görülen hemostatik bozukluklar konjenital veya kazanılmış olabilir [11]. Koagulasyon testleri pek çok çocukta aile öyküsüne veya geçmişteki kanama hikayesine bağlı olarak yapılır [12].…”

“…Koagulasyon testleri pek çok çocukta aile öyküsüne veya geçmişteki kanama hikayesine bağlı olarak yapılır [12]. En uygun tedaviyi uygulamak için doğru tanı koymanın kritik önemi vardır [11]. Anormal tarama testleri ileri araştır-malarda prosedürde gecikmelere, aile ve klinisyen için çeşitli zorluklara neden olmaktadır [12].…”

The Influence of Age on in vitro Plasmin Generation in the Presence of Fibrin Monomer

“…There are age-related, biologically important, differences in both the coagulation system and fibrinolytic system at birth and throughout childhood [2]. At birth, all components of the fibrinolytic system are present but with differing plasma concentrations of key components and evidence of significant, transient activation with plasmin generation [3].…”