[Persistent vomiting, lethargy, unexplained encephalopathy]

Suspected IEM

Plasma NH₃

Increased ABG

Normal ABG

No acidosis Urea cycle defects (No ketosis)

Acidosis

No Ketosis • Fatty acid oxidation defects

Ketosis • Organic acidemias • Mitochondrial defects

- PKU - Galactosemia - Amino acidopathies - Peroxisomal disorders