PROTHROMBIN IN NEWBORNS AND DURING THE FIRST YEAR OF LIFE

Prothrombin concentration, determined specifically with a new two-stage method, was compared with thrombotest activity in samples from infants, aged 0–21 days. There was a significant correlation between the two methods. Effect of treatment with vitamin K and plasma was registered with both methods. As the distribution of prothrombin and thrombotest values from normal, full-term neonates was slightly skew, mean value and S.D. was calculated from the logarithmic values. The normal range, expressed as mean ± 2 S.D. was for prothrombin 26–85 % and for thrombotest 27–74% (values corrected for hematocrit). No bleeding was observed in any patient with prothrombin above 20% and thrombotest above 22% (corrected values). Most low values in newborns were found in children suffering from hypoxia. Prothrombin concentration was also compared with prothrombin-proconvertin activity in samples from children, aged 0–12 months. In the healthy child prothrombin values reached the normal adult level at the age of 6–12 months, prothrombin-proconvertin values at the age of about 3 months.