hyperammonemia

Introduction

Increased levels of ammonia in blood.

Etiology

• inherited (see Genetics)
• acquired (see ammonia in plasma)

Genetics

• inborn metabolic disorders of the urea cycle
  • • increased fasting NH3
      • hyperammonemia type 1
      • argininemia
      • ornithinemia
    • increase following protein intake
      • hyperammonemia type 2
      • citrullinuria
      • argininosuccinic aciduria
      • lysine intolerance
      • hyperlysinuria
      • dibasic aminoaciduria type 2
  • CPS1 deficiency

Laboratory

• if plasma ammonia is < 100-150 umol/L, no further diagnostic testing is indicated
• arterial blood gas
• serum chemistries
  • serum lactate, serum glucose, electrolytes, anion gap,
• plasma citrulline
• 24 hour urine orotic acid

Management

• rehydration with maintenance of good urine output
• hemodialysis for plasma ammonia > 200 umol/L
• sodium phenylacetate & sodium benzoate (Ammonul) (investigational)
• reduced protein intake
• minimization of enterohepatic circulation by reducing fecal transit time
  • lactulose
  • sorbitol

More general terms

• sign/symptom

More specific terms

• hepatic encephalopathy
• ornithine hyperammonemia; ornithine carbamoyltransferase deficiency

Additional terms

• ammonia in blood