Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome (triple H syndrome) is a disorder of urea cycle metabolism characterized by either a neonatal-onset with manifestations of lethargy, poor feeding, vomiting and tachypnea or, more commonly, presentations in infancy, childhood or adulthood with chronic neurocognitive deficits, acute encephalopathy and/or chronic liver dysfunction.
