Plasma (red EDTA-K paediatric tubes). The sample MUST be received on ice within 30 minutes of venepuncture.
8hrs
Hyperammonemia in infants can be caused by inherited deficiencies of the urea cycle enzymes or acquired through acute (as in Reyes syndrome) or chronic liver disease (as in cirrhosis). In adults, elevated ammonia levels can aid in diagnosis of liver failure or hepatic encephalopathy from advanced liver diseases such as viral hepatitis or cirrhosis.
The anticoagulants fluoride, citrate and heparin must not be used. Sodium cefoxitin causes artificially high ammonia values when used at therapeutic doses. Sulfasalazine and sulfapyradine at therapeutic concentrations may cause falsely low or high results. Elevated gamma-globulin concentrations significantly increase the apparent ammonia concentration.
• <28 days: <100 umol/L
• ≥28 days: <50 umol/L
(Reported reference range for ammonia is for full-term neonates.
Reference range for sick or premature neonates: <150 umol/L
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