Univariate tolerance regions for fibrinogen, antithrombin III, protein C, protein S, plasminogen and alpha 2-antiplasmin in children using the new Automated Coagulation Laboratory (ACL) method.

To avoid misclassification of lowered or enhanced coagulation proteins in childhood the purpose of this study was to establish functional normal ranges for healthy children aged 6 months to 16 years. PT, aPTT, fibrinogen, antithrombin III, protein C, protein S, plasminogen and alpha 2-antiplasmin were tested using the new Automated Coagulation Laboratory (ACL) method. Values for PT, aPTT, fibrinogen, antithrombin III, plasminogen and alpha 2-antiplasmin were closely comparable in all children although we found a minimum range of 61% in children aged 8 to 16 years in plasma concentrations of alpha 2-antiplasmin. Children < 2.5 years showed reduced lower boundaries encompassing 95% of the population for protein C and protein S activity, although medians for protein S activity were similar in all children. The rapid and automatic determination of functional coagulation proteins using chromogenic substrates on the ACL 300 (25-50 microliters citrated plasma/test) renders the possibility to realize a screening program for inherited thrombotic syndromes in a routine laboratory.