[Propionic acidemia: clinical diagnosis vs newborn screening]

Propionic acidemia is a rare metabolic disease (prevalence 1/100,000) that can be early detected with the newborn metabolic screening within the first 72 hours of life. It can have a severe neonatal presentation, a late intermittent onset or a chronic and progressive course. The treatment in the crisis consists in inverting the catabolism by pausing the protein intake and giving intravenous non-protein calories. Mortality depends mainly on acute episodes of decompensation, while evolution and prognosis associate a high rate of neurological sequelae and cognitive deficiencies. We present the case of an 11-day-old female newborn with failure to thrive, lethargy, metabolic acidosis and hyperammonemia that, because of a failed newborn screening process, could not be early diagnosed. In spite of the existence of early detection with the newborn metabolic screening, it is very important to keep a high suspicion in cases that suggest metabolic disorders.