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HelpTest ID: NH3V Ammonia, Plasma
Useful For
Assisting in the diagnosis of hepatic coma
Investigating and monitoring treatment for inborn errors of metabolism
Evaluating patients with advanced liver disease
Reporting Name
Ammonia, PSpecimen Type
Plasma EDTAShipping Instructions
Plasma must be separated from cells and frozen within 2 hours of collection. Freeze plasma on dry ice or in a freezer (-60 to -80° C) for long-term storage or shipment.
Specimen Required
Collection Container/Tube: Lavender top (EDTA)
Submission Container/Tube: Plain, plastic screw-top tube
Specimen Volume: 0.5 mL or more
Collection Instructions:
1. Specimens should be put on ice immediately after collection.
2. Centrifuge at refrigerated temperature (4° C).
3. Aliquot plasma into plastic screw-top tube. Keep on ice.
4. Freeze plasma within 2 hours of collection.
Specimen Minimum Volume
See Specimen Collection
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma EDTA | Frozen (preferred) | 7 days | |
| Refrigerated | 2 hours |
Clinical Information
Ammonia is a waste product of protein catabolism; it is potentially toxic to the central nervous system. Increased plasma ammonia may be indicative of hepatic encephalopathy, hepatic coma in terminal stages of liver cirrhosis, hepatic failure, acute and subacute liver necrosis, and Reye's syndrome. Hyperammonemia may also be found with increasing dietary protein intake.
The major cause of hyperammonemia in infants includes inherited deficiencies of urea cycle enzymes, inherited metabolic disorders of organic acids and the dibasic amino acids lysine and ornithine, and severe liver disease.
Reference Values
≤30 mcmol/L
Interpretation
Plasma ammonia concentrations do not correlate well with the degree of hepatic encephalopathy.
Elevated ammonia concentration may also be found with increased dietary protein intake.
Plasma ammonia concentrations in newborns younger than one week are elevated compared to adults. Values less than or equal to 82 mcmol/L have been observed.(1)
Clinical Reference
1. Madigan T, Block DR, Carey WA, et al: Proposed plasma ammonia reference intervals in a reference group of hospitalized term and preterm neonates. J App Lab Med. 2020 Mar 1;5(2):363-369
2. Rosenberg W: Liver disease. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:1348-1397
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 dayTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82140
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| NH3V | Ammonia, P | 16362-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| NH3V | Ammonia, P | 16362-6 |
Method Name
Photometric, Bromophenol Blue
mml-liver-pancreatic