Check for ammonia immediately in
infants, children, or adults with unexplained:
GI presentations
Alterations in consciousness
Encephalopathy
Learning problems or developmental delays
Psychiatric presentations
Movement disorders
or seizures
Delayed recognition and treatment of hyperammonemia
may result in irreversible neurological damage or death.
Neurological Presentations
Confusion, lethargy, dizziness
Migraine-like headaches
Tremor, ataxia, dysarthria
Intellectual/learning disabilities, neurodevelopmental delay
Seizures
Hemiplegia
Coma
Psychiatric Presentations
Behavioral changes, mood alteration, hyperactivity, aggressiveness, combativeness
Delusions, psychosis
Sleep disorders
Gastrointestinal Presentations
Abdominal pain, nausea, vomiting
Protein aversion, self-selected low-protein diet
Failure to thrive
Hepatomegaly, elevated liver enzymes
Go beyond liver disease
Think inborn errors of metabolism
In older individuals, hyperammonemia is often the consequence of a diseased liver.
Even in patients with known hepatic disease, clinicians should consider other reasons for their hyperammonemia, such as late-onset urea cycle disorder (UCDs) or other inborn errors of metabolism. UCDs affect neonates, but 69% of people with UCDs first present with symptoms later in life.
If high plasma ammonia levels are detected in an infant, child, or adult, differential diagnosis can rule out many different disorders that may be causing the hyperammonemia.
Inborn errors of metabolism that may cause hyperammonemia
- Urea cycle disorders (UCDs)
- Organic acidemias, such as propionic acidemia (PA) or methylmalonic acidemia (MMA)
- Tyrosinemia type 1
Galactosemia - Mitochondrial disorders
- Fatty acid oxidation disorders
- Citrin deficiency leading to citrullinemia type II (CTLN2)