Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (689 page)

   Total parenteral nutrition.

   Smoking, exercise, valproic acid therapy.

Decreased In

   Hyperornithinemia (deficiency of ornithine aminotransaminase activity) with gyrate atrophy of the choroid and retina

   Limitations

   Atmospheric ammonia may cause falsely elevated results.

   The presence of ammonium ions in anticoagulants may produce falsely elevated results.

   Ammonia levels are not always high in all patients with urea cycle disorders.

   High-protein diet may cause increased levels.

   Ammonia levels may also be elevated with GI hemorrhage.

   Ammonia increases due to cellular metabolism: 20% in 1 hour and 100% by 2 hours.

   Prolonged tourniquet application can falsely raise blood ammonia levels.

AMNIOCENTESIS

See Prenatal Screening.

AMPHETAMINES
*

   Definition

   Sympathomimetic amines with central nervous system stimulant activity.