Blood Gases, Plasma Ammonia Levels and Urine Analysis; a Potential for Early Detection of Some Inborn Errors of Metabolism

Aims: Inborn errors of metabolism (IEM) constitute a group of inherited disorders that cause significant morbidity and mortality. This diverse group of diseases present with different clinical manifestations that make the diagnosis a real challenge. The current work aimed to investigate the potential of some preliminary laboratory tests such as blood gases, plasma ammonia levels and urine analysis as rapid and conventional biochemical markers for early diagnosis of young children with high suspicion of metabolic disorders.

Methodology: The present study has been conducted on 50 patients suspected to have metabolic disorder according to the inclusion criteria selected from pediatric patients attending the pediatric, metabolic and neurological consultant clinics at the Pediatrics Department, Assiut university hospital, Egypt. In addition, to 20 healthy subjects were selected as the control group who had matched age and sex to the study group. All participants had their blood tested for complete blood count, gases, ammonia, electrolytes, urea, creatinine and glucose levels. Additionally, urine was tested for ketonuria, cysteinuria and fructosuria. Computed topography (CT) and cerebrospinal fluid (CSF) studies were also performed.

Results: There was a significant higher percent of consanguineous marriage among the patients’ parents compared with the control group. Plasma ionized calcium, pO2 and ammonia levels were significantly higher (p ˂0.05), whilst, pCO2, pH and HCO3 were lower (p ˂0.05) in patients versus the control group. One case had ketonuria and hyperglycemia but died before completing the investigatory workup. CT brain revealed that 60% of the included pediatric patients had brain atrophic changes. The final diagnoses of patients suspected to have metabolic disorders were: 11 (22%) had septicemia; 21 (42%) died before complete the final diagnosis; 12 (24%) suspected to have urea cycle defect and 6 (12%) suspected to have organic acidemia.

Conclusions: Blood gases, plasma ammonia levels and urine analysis are collectively simple and rapid laboratory tests that can give a preliminary indication for further investigations in pediatric patients with suspicious symptoms of metabolic disorders.