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HelpOrder Code 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 |
|---|---|---|
| Plasma EDTA | Frozen (preferred) | 7 days |
| Refrigerated | 2 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
≤30 mcmol/L
Method Description
Patient specimen is deposited on the slide where the spreading layer promotes the uniform distribution of the specimen. Water and nonproteinaceous components travel to the underlying buffered reagent layer. The ammonia in the sample then diffuses through the semipermeable membrane to react with the ammonia indicator in the second reagent layer. The semipermeable membrane allows only the ammonia to pass and prevents buffer or hydroxyl ions from reaching the indicator layer where they would react with the indicator. After a fixed incubation period, the reflection density of the dye is measured using the white background of the spreading layer as a diffuse reflector.(Package insert: VITROS Chemistry Products Ammonia Instructions for Use, Version 11.0 Ortho-Clinical Diagnostics, Inc; 2019)
Day(s) Performed
Monday through Sunday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82140
Method Name
Photometric, Bromophenol Blue