Objective: Transient immaturity of some metabolic enzymes, such as the 4-hydroxyphenylpyruvic acid dioxygenase enzyme, during the neonatal period may lead to elevated plasma tyrosine levels. Most infants are asymptomatic, but some have lethargy and poor feeding. However, there are not enough articles showing the relationship between the transient tyrosinemia and prolonged jaundice in newborns. Therefore, we aimed to present the demographic and clinical features of newborns with prolonged jaundice and transient tyrosinemia.

Materials and Methods: The files of infants who were admitted to newborn polyclinic due to prolonged jaundice between January-2010 and December-2010, and had transient tyrosinemia in blood aminoacid chromatography were examined retrospectively. Having tyrosine levels higher than 150 μmol/L (normal: 2-150 μmol/L) and decline of these values back to normal level in 4-6 weeks was considered as “transient tyrosinemia of the newborn”.

Results: 8 of 10 infants (80%) were male and 2 infants (20%) were female. All of the cases were full-term babies with a mean birth weight of 3443±357 g (range: 2860-4075 g). The mean peak bilirubin level was 15.3±2.4 mg/dL (range: 11.3-20.8 mg/dL) and the mean duration of jaundice was 48.8±11.8 days (range: 30-72 days). The mean serum tyrosine level was 190.1±28.5 μmol/L (range: 158-238 μmol/L) at the time of diagnosis and the control serum tyrosine level was 94.7±35.0 μmol/L (range: 47-144 μmol/L) after 4-6 weeks. Complete blood count, liver function tests, thyroid function tests, glucose-6-phosphate dehydrogenase enzyme levels, and urine tests, which were performedto investigate the cause of prolonged jaundice, were found to be normal in all cases.

Conclusion: The transient tyrosinemia of the newborn should be taken into consideration in the etiology of prolonged jaundice.