Selective screening in neonates suspected to have inborn errors of metabolism

Abstract

Background: Inborn errors of metabolism (IEM) have a high morbidity and mortality in
neonates. Unfortunately, there is no nationwide neonatal screen in Egypt, so several cases may be missed.
Objective: The aim of this work was to detect the prevalence of IEM among neonates with suspected IEM, and to diagnose IEM as early as possible in order to minimize morbidity and mortality in high risk neonates.
Subjects and methods: This prospective study included 40 neonates admitted to the Elmahalla General Governmental Hospital Neonatal Intensive Care Unit (NICU) with sepsis like symptoms (lethargy, hypoactivity, poor suckling, and poor crying), convulsions, persistent metabolic acidosis, persistent vomiting, or previous sib death of unidentified cause (neonates with suspected IEM). All included patients were subjected to detailed full history, through clinical examination, laboratory investigations, and metabolic screening by tandem mass spectrometry (MS/MS). Other investigations for IEM including lactate, ammonia, and galactose 1 phosphate levels in the blood, as well as organic acids in urine were done according to each case.
Results: 13 patients (32.5%) were diagnosed as having IEM, 7 of them (53.8%) had urea cycle defect, 2 (15.4%) had maple syrup urine disease, while methylmalonic acidemia, fatty acid oxidation defect, mitochondrial disease, and galactosemia were diagnosed in one patient each (7.7%). Out of these patients, 12 patients (30%) were discharged from NICU after therapy, and one patient (2.5%) died (the one who had mitochondrial disease). Two patients were diagnosed as diseases other than IEM, one had hyperinsulinism and another one had congenital myopathy, while 2 patients were proved to be normal. Five patients (12.5%) were suspected to have IEM (tyrosinemia, mitochondrial disease, organic acidemia) 4 of them died before final diagnosis, and one transferred to another NICU. There was a significant difference between diagnosed and undiagnosed patients as regards history of sibling death (p= 0.012), plasma ammonia level (p= 0.002), and discharge from NICU (p= 0.000).
Conclusion: IEM represent a high percent (32.5%) of neonates who had sepsis like symptoms, and when diagnosed, patients showed marked improvement after therapy. IEM should be considered in differential diagnosis of the sick neonates, and investigations, and management should be started rapidly to decrease morbidity, and mortality till nationwide screen for IEM is applied in Egypt.