Relationship between serum bilirubin and coagulation test results in 1-month-old infants

Although the connection between cholestasis and conjugated hyperbilirubinemia is well known, mild hepatic dysfunction or cholestasis may also be associated with unconjugated hyperbilirubinemia in some infants with prolonged jaundice. The aim of this study was to investigate the relationship between serum bilirubin levels and alanine aminotransferase levels, aspartate aminotransferase levels, prothrombin time, activated partial thromboplastin time, and international normalization ratio findings in a group of infants.

The study included 77 healthy, term, breast-fed infants with jaundice and 56 age-matched, healthy, term, non-jaundiced controls. The 133 babies were divided into three subgroups according to their total bilirubin levels [group I (controls) < 50 micromol/L, group II = 50-100 micromol/L, and group III > 100 micromol/L, and the findings for the noted parameters were compared].

The mean conjugated bilirubin level was significantly higher, and the mean activated partial thromboplastin time significantly longer in group III than in group I. A significant positive correlation was found between bilirubin levels and PT and APTT results.

Clinical vitamin K deficiency appeared unlikely to develop in this group of infants with prolonged unconjugated hyperbilirubinemia. However, a significant positive correlation between bilirubin levels and PT and APTT suggest that a higher bilirubin load to the liver may cause some degree of vitamin K deficiency due to mild cholestasis. The importance of this finding, and the possible benefits of vitamin K supplementation in 1-month-old breast-fed infants with bilirubin levels higher than 100 micromol/L require further investigation.