Prevalence and patterns of abnormal metabolic screening in pediatric acute encephalopathy: a PICU study from Egypt

Abstract

BACKGROUND: Inborn errors of metabolism (IEMs) remain underrecognized in children presenting with acute non-infectious encephalopathy, where timely diagnosis and treatment can be lifesaving. This study sought to estimate the yield and spectrum of metabolic screening patterns suggestive of IEM among children with presumed non-infectious acute encephalopathy admitted to a tertiary pediatric intensive care unit in Egypt. METHODS: From March 2023 to June 2024, we undertook and finalized a cross-sectional research study at the Minia University PICU. After initial clinical evaluation, cerebrospinal fluid (CSF) analysis did not support overt central nervous system infection; children with presumed non-infectious acute encephalopathy were enrolled. They underwent standardized clinical, laboratory, and neuroimaging workups. Metabolic screening comprised tandem mass spectrometry (TMS) of amino acids/acylcarnitines and urine organic acids by gas chromatography-mass spectrometry (GC-MS). N = 100 participants were included. RESULTS: Abnormal metabolic screening suggestive of an underlying IEM was identified in 26% (n = 26) of children with non-infectious encephalopathy (NIE). The most common abnormal profiles were amino acid disorders (38.5%), organic acidemias (34.6%), and fatty acid oxidation defects (26.9%). Overall mortality was 59%. Abnormal screening was associated with higher ammonia levels (median 176 vs 65 μmol/L; p < 0.001) and a higher frequency of cognitive delay, delayed motor development, and hypotonia (all p < 0.05). On ROC analysis, ammonia > 93.5 μmol/L predicted abnormal screening (sensitivity 84.6%, specificity 65%). In univariate logistic regression, higher serum ammonia, cognitive delay, and delayed motor development were associated with abnormal metabolic screening. In a parsimonious multivariable model, higher ammonia (adjusted OR 1.010, 95% CI 1.004-1.015; p = 0.001) and delayed motor development (adjusted OR 3.66, 95% CI 1.24-10.86; p = 0.019) remained independent predictors. CONCLUSIONS: Abnormal metabolic screening suggestive of IEMs comprises a substantial proportion of pediatric NIE in our setting. Early metabolic screening coupled with readily available biomarkers (notably ammonia) may help prioritize patients for confirmatory testing and timely management.