Any episode of acute hyperammonemia should be treated as a life-threatening emergency

People with NAGS deficiency, Propionic Acidemia or Methylmalonic Acidemia may experience acute high blood ammonia levels. At high levels, ammonia is toxic (or poisonous), especially to the brain. Lowering high blood ammonia levels quickly is key.

High blood ammonia levels can occur for many years before diagnosis

Some people have episodes of high blood ammonia for many years before being properly diagnosed and treated. This happened to Mary, who was eventually diagnosed with NAGS deficiency.