Evaluating the Incidence, Risk Factors, and Diagnostic Limitations of Transient Neonatal Tyrosinemia in Iranian Newborns

Saeideh  Abdolahpour; Maryam  Nasri; Farzaneh  Abbasi; Reihaneh  Mohsenipour; Maryam  Khazdouz; Farshad  Sharifi; Sedigheh  Shams

doi:10.18502/abi.v3i2.19487

Saeideh Abdolahpour Growth and Development Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
Maryam Nasri Growth and Development Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
Farzaneh Abbasi Growth and Development Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
Reihaneh Mohsenipour Growth and Development Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
Maryam Khazdouz Hazrat-e Ali Asghar Children’s Hospital, Iran University of Medical Sciences, Tehran, Iran
Farshad Sharifi Elderly Health Research Center, Tehran University of Medical Sciences, Tehran, Iran
Sedigheh Shams Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/abi.v3i2.19487

Keywords: Transient Neonatal Tyrosinemia, Neonatal Screening, Newborn, Cesarean Section, Premature Birth, Iran

Abstract

Objectives: Transient Neonatal Tyrosinemia (TNT) is a benign, self-limiting condition characterized by elevated blood tyrosine levels in neonates. It is typically caused by immature hepatic enzymes, particularly 4-hydroxyphenylpyruvate dioxygenase (4-HPPD), and may be influenced by factors such as prematurity, low birth weight, and high protein intake. Early detection through newborn screening is critical to distinguish TNT from more severe disorders such as tyrosinemia type I. This study aimed to determine the incidence of TNT and identify perinatal factors associated with its development in Iranian neonates.

Methods: This retrospective case-control study analyzed newborn screening data from the Growth and Development Research Center’s metabolic laboratory between March 2019 and February 2023. Infants with normal screening results during the same period were included as the control group.

Results: A total of 73,349 infants underwent metabolic screening. The incidence of TNT was 0.47%, corresponding to 345 diagnosed cases. Compared to the control group, infants with TNT had lower gestational age (37.7 ± 1.4 weeks), lower birth weight (2.94 ± 0.5 kg), and a higher rate of cesarean deliveries (83.9%) (P < 0.05). Logistic regression analysis revealed significant associations between TNT and preterm birth (OR: 868.2, 95% CI: 168.9–4212.7, P < 0.001), cesarean delivery (OR: 3.5, 95% CI: 2.26–5.3, P < 0.001), and gestational age (OR: 0.17, 95% CI: 0.12–0.24, P < 0.001). No significant associations were found with other parameters (P ≥ 0.05).

Conclusion: The incidence of TNT in Iranian newborns is associated with prematurity and cesarean delivery. Optimizing screening protocols and encouraging vaginal delivery when feasible may help reduce TNT rates