Ammonia, Plasma
Use
Ammonia is elevated in the following conditions: liver disease, urinary tract infection with distention and stasis, Reye syndrome, inborn errors of metabolism including deficiency of enzymes in the urea cycle, HHH syndrome (hyperammonemia-homocitrullinuria, hyperornithinemia), some normal neonates (usually returning to normal in 48 hours), total parenteral nutrition, ureterosigmoidostomy, and sodium valproate therapy. Ammonia determination is indicated in neonates with neurological deterioration, subjects with lethargy and/or emesis not explained, and in patients with possible encephalopathy.
Special Instructions
The date and time the specimen was drawn must be written on both the tube of blood and the request form. The patient should not clench their fist during collection.
Limitations
There is a poor correlation between blood ammonia levels and hepatic coma. Ammonia determinations are not reliable predictors of impending hepatic coma and are not always elevated in all patients with urea cycle disorders. High protein diets and gastrointestinal hemorrhage can affect ammonia levels. Conditions like cirrhosis may alter hepatic blood flow, leading to elevated levels.
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 22763-7
- 22763-7
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Lavender-top (EDTA) tube; EDTA is the only acceptable anticoagulant.
Collection Instructions
Tube must be filled completely and kept tightly stoppered at all times. Mix well. Specimen must be placed on ice immediately. Separate plasma from cells within 15 minutes of collection. Transfer specimen to a plastic transport tube before freezing. Avoid contamination of samples by ammonia.
Patient Preparation
Patient should be fasting 12 to 14 hours to avoid lipemia, which interferes with the test.
Storage Instructions
Freeze. Ammonia is stable for several days at -20°C. Caution: Blood ammonia increases rapidly at room temperature.
Causes for Rejection
Hemolysis, specimen not received frozen, certain anticoagulants like citrate, oxalate, ammonium heparin, or sodium fluoride, lithium heparin, serum specimen, lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unstable |
| Refrigerated | 2 hours |
| Frozen | 3 days |