Objective: To estimate the incidence of Inborn errors of metobolism (IEM) in Neonatal intensive care unit (NICU) using tandem mass spectrometry and to determine the impact that these disorders have on NICU resources.
Methods: During the period of study, 724 (81% eligible cases) dried blood filter-paper samples were collected from a NICU. The samples were analysed using tandem mass spectrometry. The diagnosis was further confirmed through clinical symptoms and by gas chromatography-mass spectrometry. The results were also confirmed by clinical follow-up of all positive patients in an overall interval of 1 year. The mean observation period was 11 months per neonate.
Results: In total, 22 cases were screen positive and 8 cases of inborn errors of metabolism were detected. The incidence of IEM in the population of patients admitted to the authors' NICU was 1.1%. The most common inborn error found was methylmalonic acidemia (3 cases, 37.5%), and all of the cases needed aggressive treatment and invasive mechanical ventilation. There were two cases of Tyrosinemia type 1, one case each of Maple Syrup Urine Disease, Propionic Acidemia, and Multiple Acyl-CoA dehydrogenase deficiency (MADD). Five of the eight patients required invasive mechanical ventilation. The median length of NICU stay was 3 days (1~7 days) and early therapeutic intervention was effective for four of them and other four patients (50%) died.
Conclusions: The incidence of IEM in NICU was 1.1%, indicating an underestimation of the incidence of metabolic disorders prior to implementing screening. Most patients with IEM in the NICU required invasive mechanical ventilation and the mortality was increased due to underlying IEM.