Low antithrombin III in neonatal shock: DIC or non-specific protein depletion?

Low antithrombin III (AT III) levels in shock are usually ascribed to disseminated intravascular coagulation (DIC). However, decreased activities of clotting factors and their inhibitors could reflect a generalised fall in plasma proteins rather than DIC. AT III and albumin were compared in 48 asphyxiated and non-asphyxiated newborn rabbits (pH 6.70-7.30). Both AT III and albumin were markedly decreased in the sickest animals and there was a direct linear relationship between the two proteins (P less than 0.001). Similar results were obtained in ten newborn infants suffering from shock and haemorrhagic diathesis. In all cases AT III and albumin were decreased below the normal range and significantly correlated (P less than 0.01). Our findings suggest that AT III is not a useful diagnostic marker of DIC. Further, a similar fall of clottable and non-clottable proteins in shock questions the general assumption that the ensuing coagulopathy is due to intravascular coagulation.