Neonatal Cholestasis - Is it tyrosinemia_?
Author:
Pediatric Oncall
Question
A 3 month old boy born of non-consanguineous marriage presented with jaundice and clay coloured stools for 2 months. He was born at 34 weeks and had a birth weight of 2 kg but did not cry immediately after birth for which he required NICU stay for 5 days. He was currently on formula feeds. He had been investigated for jaundice and bilirubin was 7.5 mg, dl {direct = 3.7 mg, dl}, SGOT was 438 IU, L, SGPT = 140 IU, L, alkaline phosphatase was 2204 IU, L, hemoglobin was 10 gm, dl, while cell count was 8400, cumm and prothrombin time and partial thromboplastin time was normal. Ultrasound abdomen did not show gall bladder. At presentation, his weight was 3.6 kg, length was 58 cms. He had jaundice and hepatosplenomegaly. Further investigations revealed positive CMV IgM and IgG. Ophthalmological examination was normal. Echocardiography showed small ostium secundum atrial septal defect. Liver biopsy showed no biliary atresia or inclusion bodies and intraoperative cholangiogram showed passage of dyes into the intestine. Urine aminoacidogram and plasma aminoacidogram showed increased tyrosine levels. S.alpha-feto proteins were 10147 IU, ml.
He was treated with Valganciclovir which was stopped after 6 weeks along with tyrosine and phenylalanine restricted diet. At 8 months of age, serum bilirubin was 1.7mg, dl, SGOT was 121 IU, L, SGPT was 115 IU, L and Albumin was 3.9gm, dl. His serum alpha-feto protein had normalized and urine and plasma aminoacidogram were normal. He was started on regular diet. At 11 months of age, his weight was 8.9kg and his liver functions were normal.
Why did the initial aminoacidograms show increase in tyrosine levels_?
Expert Opinion :
Transient tyrosinemia of the newborn is a benign disorder of tyrosine metabolism detected upon newborn screening and often observed in premature infants. It shows no clinical symptoms. It is characterized by tyrosinemia, moderate hyperphenylalaninemia, and tyrosiluria that usually resolves without treatment. Transient tyrosinemia is believed to result from delayed enzyme maturation in the tyrosine catabolic pathway. Transient tyrosinemia is not categorized as an inborn error of metabolism because it is not caused by a genetic mutation.
In this child probably the initial UAA and PAA picked by tyrosine which may be due to immaturity of the tyrosine catabolic pathway.
Neonatal cholestasis due to tyrosinemia will not resolve.