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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Ammonia
Test CodeNH3
Alias/See Also
NH3
Preferred Specimen
1.0 mL plasma (0.5 mL minimum)
Patient Preparation
A fasting specimen is preferred.
Smoking should be avoided for at least 9 hours before sample collection.
Do not collect after physical exercise.
Instructions
A free-flowing venous (or arterial) blood sample should be collected into a specimen tube (preferably pre-chilled).
Do not collect via indwelling catheters or capillary puncture.
The tube should be completely filled and stored tightly capped on ice.
Transport the sample on ice IMMEDIATELY to the lab.
Samples that are not received within 30 minutes of collection will be rejected.
Do not collect via indwelling catheters or capillary puncture.
The tube should be completely filled and stored tightly capped on ice.
Transport the sample on ice IMMEDIATELY to the lab.
Samples that are not received within 30 minutes of collection will be rejected.
Transport Container
Lithium heparin (PST mint/light green-top tube)
Transport Temperature
On ice, deliver to lab immediately
Specimen Stability
Room temperature: Unacceptable, Refrigerated: 2 hours (separated sample), Frozen: Unacceptable
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolyzed or lipemic specimens are unacceptable.
Samples that are not received on ice are unacceptable.
Specimens that are received greater than 30 minutes after collection will be rejected.
Samples that are not received on ice are unacceptable.
Specimens that are received greater than 30 minutes after collection will be rejected.
Reference Range
11-32 umol/L
Clinical Significance
The bulk of ammonia in the body is generated by the gastrointestinal system by action of bacterial enzymes on the contents of the colon and from hydrolysis of glutamine. It is removed in the liver and converted to urea through a series of enzymatic reactions in the Krebs-Henseleit cycle. Among other conditions, advanced liver disease and hepatic encephalopathy result in elevated levels of ammonia in blood. Hyperammonemia is also common in inherited deficiencies of the enzymes involved in the conversion of ammonia to urea. The determination of ammonia is very useful in the diagnosis and prognosis of Reye's Syndrome. Elevated blood ammonia exerts toxic effects on the central nervous system.
