Abstract • 130

In our laboratory we measured antithrombin (AT, chromogenic assay), protein C (PC, chromogenic assay) and protein S (PS, Elisa) levels in the following groups: healthy premature (n: 20) and full term infants (n:20) sick neonates suffering from RDS or septicaemia (n: 25), healthy children (n: 269) aged 1-14 years (mean: 6), and children suffering from meningococcal septicaemia (n: 37). Results: AT, PC and PS values were found considerably lower in premature and full term infants as compared to children of older age. A more significant reduction in natural inhibitors of haemostasis was found in diseased infants suffering from RDS. Despite of that, none of the healthy or diseased neonates presented with clinical manifestations of thrombosis. However aortic thrombosis was documented by high resolution real-time ultrasonography in 3/25 (12%) catheterized infants, mainly suffering from RDS. A proportion of healthy children presented with PC (10%) and PS (6.3%) values below the lower limits of normal for healthy adults. Considerably decreased AT, PC and PS values were found in children suffering from meningococcal septicaemia. PC deficiency was more severe than AT and PS deficiency and was mostly related to purpura fulminans, multiple organ failure and lethal outcome. Comment: Normal physiological changes of natural inhibitors of haemostasis in neonates or children do not seem to predispose the healthy infant or child to thrombotic complications, however in disease states such as RDS or septicaemia, the defect becomes more pronounced and may be associated with thrombosis symptomatic or asymptomatic.