Hyperammonemia

Background

Pathophysiology

  • Acquired: liver failure results in shunting of blood from the liver to the inferior vena cava, decreased filtration of blood and removal of nitrogen-containing toxins by the liver, and then hyperammonemia.
  • Congenital: Defect in one of the enzymes of the urea cycle, which leads to lower production of urea from ammonia.

Types

  • Primary
  • Secondary
    • Caused by inborn errors of intermediary metabolism (i.e. reduced activity of enzymes that are not part of the urea cycle)

Clinical Features

Differential Diagnosis

Evaluation

Acquired vs. Congenital

  • Acquired
    • Diseases that result in liver failure
    • Medications (e.g. valproic acid overdose)
    • Severe dehydration (from small intestinal bacterial overgrowth)
    • Glycine toxicity (CNS symptoms and nausea)
  • Congenital
    • Genetic

Management

  • Treat underlying disorder

Disposition

  • Depends on cause

See Also

External Links

References