抄録
Factor IX activity (IX: C) and factor IX antigen (IX: AGN) (Laurell method) were measured in 140 full-term newborn infants with no hemorrhagic sympotoms during the first week of life, and crossed immunoelectrophoersis was performed for qualitative analysis of factor IX. IX: C and IX: AGN in the newborn plasma were lowest on the first day of life, i. e., 24.4±8.2 and 23.4±6.3% respectively, and rose gradually during the first week, reaching 52.6±5.8 and 53.9±7.4% respectively. On the crossed immunoelectrophoresis of IX: AGN in the presence of 1mM calcium lactate, a biphasic arc was observed in 16 newborn plasmas, i. e., in 20, 35, 25 and 10% respectively, in the first 13-24 hours, the second day, the third day and the fourth day. IX: C of these plasmas was apparently low in contrast to IX: AGN. One arc lay in normal factor IX position and the other arc shifted faster to the anode, suggesting the presence of abnormal factor IX. This anodal arc and the anodal arc of plasma obtained from dicumarol treated patient or chronic hepatitis were the same mobility on the crossed immunoelectrophoresis. From this study, the abnormal factor IX which occurs in the newborn period was regarded as PIVKA IX (protein induced by Vitamin K absence or antagonist).
