The metabolism and excretion of bile pigment in icterus neonatorum

Abstract

<h2>Summary</h2> We have conducted a series of investigations upon newborn infants in an attempt to elucidate the conditions upon which the development of icterus neonatorum depends. The results may be summarized as follows: The average amount of blood destruction in the groups of jaundiced and nonjaundiced infants is essentially the same. The amount of blood destruction in different individuals of both groups, however, varies considerably. The bile pigment in the blood never gave the prompt direct reaction with the van den Bergh reagent, whether the infants were jaundiced or not. In practically all patients showing jaundice the indirect (quantitative) van den Bergh reaction showed 5 units or more of bilirubin. Only a few of the patients without jaundice showed more than 5 units of bilirubin in the blood. Bilirubin was present in the urine of practically all the patients with jaundice. Conversely it was absent in practically all the patients without jaundice. it appears to depend upon the level of bile pigment in the blood rather than upon the presence of a prompt reacting pigment. The excretion of bile pigment in the stools was studied during the first week of life. High values for urobilin and bilirubin (including biliverdin) were obtained during this period. In the patients with jaundice the average total excretion was lower than in those without jaundice. This was contrary to what one would expect in a purely hemolytic type of jaundice. The excretion of urobilin and bilirubin in the urine was studied in the same group of cases. As in the stools, the average total urobilin excretion was lower in the patients with jaundice than in the nonjaundiced group. Bilirubin was present in measurable quantities in all cases with jaundice. In the cases without jaundice it was nearly always absent. It would appear from the evidence we have brought forward that obstruction of the bile channels plays no part in the production of icterus neonatorum. The jaundice appears to depend upon two factors. The first and basic factor is the excessive hemolysis and resultant increase in circulating bile pigment which takes place in varying degree in all newborn infants. There does not appear, however, to be an excessive hemolysis taking place in the blood of those infants developing jaundice. Some factor would appear to be at work to prevent the excretion of bile pigment in these infants. It may be an increased affinity of certain tissues in these infants for bile pigment. What appears more likely is that the liver cells of these infants have a temporary functional inability to excrete the bile pigment. The histologic observations of Snelling³ lend support to this thesis. Possibly the prevalence of jaundice in the premature infant may be due to the immaturity and consequent functional disturbance of the liver cells.