Zinc, copper and magnesium levels were determined in the sera of mothers and the umbilical cords of 66 newborn babies to shed light on the causes of hyperbilirubinemia of unknown etiology of the newborn, encountered frequently in Turkey. Grouping the babies according to their bilirubin levels at 48 hours of age, zinc and magnesium were found to be significantly low in those in whom bilirubin levels were over 8 mg/dl.

The zinc and magnesium levels were also low in the sera of another group of 30 neonates in whom hyperbilirubinemia was high enough to necessitate exchange transfusion, when compared with a control group. Since zinc and magnesium are found mostly in proteins, hyperbilirubinemia of unknown etiology is believed to be due to nutritional disorders. The significance of zinc and magnesium deficiency in bilirubin metabolism is discussed.

Keywords: bilirubin metabolism, copper, hyperbilirubinemia of unknown etiology, magnesium, trace elements, zinc