Coagulation testing in pediatrics: the young are not just miniature adults.

During the past few decades, great progress has been made toward a better understanding of the development of the hemostatic system. It is now clear that the physiology of hemostasis in pediatric patients differs widely from that in adults, supporting the hypothesis that children might have natural protective mechanisms that justify such variations. However, the correct interpretation of hemostasis test results in young patients, along with a deep understanding of the normal postnatal development in the human coagulation system, are essential prerequisites to the proper investigation of thrombotic and hemorrhagic problems in pediatric patients. Because the hemostatic system is not fully mature by 3 to 6 months of age, it is important to recognize that interpretation of laboratory data in pediatric patients must be accompanied by appropriate age-dependent reference ranges, which should also be specific for the testing system used, to prevent misclassification of children as having defects of factors and inhibitors of the coagulation system. Copyright © 2007 by Thieme Medical Publishers, Inc.