[Thrombocytosis and reduced levels of factor VIII in rheumatoid purpura in children].

Thirty three patients with Henoch-Schoenlein purpura were studied at various developmental stages of this disease: specially platelet counts and factors XIII and VIII. During the development phases: 40,6% of the patients have a slight but regressive thrombocytosis (greater than 400 G/l); and 75% a reduced factor XIII, well correlated with the severity of the clinical status (level as low as 60% can be considered as a "gravity threshold"), and corrected during the improvement of the disease. This reduced factor XIII is probably linked to the local inflammation in the vessels. Factor VIII studies (specially VIII A: Ag) were normal.