Tahia H. Saleem - Medical Biochemistry Department, Faculty of Medicine, Assiut University, Assiut, Egypt.
Nagwan I. Rashwan - Pediatric Department, Faculty of Medicine, South Valley University, Qena, Egypt.
Mohammed H. Hassan - Medical Biochemistry Department, Faculty of Medicine, South Valley University Qena, Egypt.
Bahaa Hawary - Pediatric Department, Faculty of Medicine, Aswan University, Aswan, Egypt.
Doha Abd-Elraheim Salama - Medical Biochemistry Department, Faculty of Medicine, South Valley University Qena, Egypt.
Nahed A. Mohamed - Medical Biochemistry Department, Faculty of Medicine, Assiut University, Assiut, Egypt.
Mohamed Elsayed Mohamed Ahmed - Chemistry Department, Faculty of Science, Sohag University, Sohag, Egypt AND Analytical Biochemistry Diploma, Chemistry Department, Faculty of Science, Menoufia University, Menoufia, Egypt.
Eman Ahmed Abd-Elmawgood - Pediatric Department, Faculty of Medicine, South Valley University, Qena, Egypt.

Background: The diagnosis of inborn errors of metabolism is generally challenging. We aimed to explore various types of urea cycle disorders (UCDs), and their clinical presentations and biochemical findings among Egyptian pediatric patients. Materials and Methods: This case-control study was conducted on ۸۶ participants categorized into ۴۳ pediatric patients suspected to have UCDs and ۴۳ age- and sex-matched healthy controls, recruited from the Pediatric Outpatient Clinics, Inpatients Pediatric Departments, PICU and Neonatal Intensive Care Units of Qena, Assiut and Aswan University Hospitals, Egypt. In addition to the clinical assessments and routine laboratory investigations, colorimetric assays of blood lactate and ammonia, and plasma free amino acids assays using high performance liquid chromatography (HPLC), were performed for all included children. For patients with abnormal aminograms, the five enzymes of the urea cycle were measured in their liver tissue homogenates, using chemical methods. Results: The results showed that ۲۵ out of ۴۳ suspected patients were confirmed to have UCDs. The most frequent type of UCDs was Ornithine transcarbamylase (OTC) deficiency (۴۸%), followed by Argininosuccinate synthase (ASS) deficiency (۳۶%) and the least frequent was arginase (ARG) deficiency (۱۶%). The main clinical presentations were poor oral intake (۱۰۰%), followed by lethargy (۹۶%), hypotonia (۶۸%), vomiting (۶۴%), and hepatomegaly (۴۸%). There were normal glucose and ABG values with significantly higher ammonia; lactate and the measured plasma free amino acids among patients with UCDs vs. the controls (p˂۰.۰۵). Conclusion: The most frequent types of UCDs among pediatric patients in Upper Egypt were OTC and ASS deficiencies. In addition to clinical suspicion, assays of lactate, ABG, glucose, ammonia and aminogram may be helpful biochemical tests in diagnosing UCDs.

Argininosuccinate synthase, Hyperammonemia, Ornithine transcarbamylase, Arginase, Urea cycle disorders, Pediatric, Upper Egypt