H–18
IDEXX VetTest* Chemistry Analyzer Operator’s Manual
Ammonia/NH
3
Ammonia is the catabolic product of protein digestion and is extremely toxic. It is
converted rapidly in the liver to urea which is eliminated from the body by the kidneys.
Principal reason for performing the test:
To detect a portosystemic shunt.
Most common abnormality indicated by the test:
Portosystemic shunt
Special precautions in sample collection:
Blood should be processed and centrifuged immediately following collection. For this
reason, plasma is recommended as the sample of choice.
Ammonia measurements in either plasma or serum are significantly affected by
environmental factors and/or the passage of time. Minimal exposure of the sample to
the air is essential. All sample containers should be capped unless sample is being
introduced or withdrawn. Do not attempt to measure ammonia in hemolyzed samples.
Contamination from the red cells will invalidate the test.
Limitations of procedure:
The following preparation and environmental factors can result in elevated ammonia
values:
Allowing red blood cells and plasma/serum to remain in contact even for a brief t
period
Use of serumt
Cigarette smoket
"NNPOJBCBTFEDMFBOFSTt
"NNPOJBPSMBUFYCBTFEQBJOUTt
/PO7FU5FTUBOBMZ[FSDPWFSTt
Magic markers/penst
Hand creamst
Decomposing urinet
Urinet
Important: For optimum performance, ammonia testing should NOT be done when
UREA/BUN slides are in the same run. Do not use cleaning solutions or hand creams
that contain ammonia in the area of the analyzer.
Complementary tests:
Ammonia may be determined in isolation but more usually in conjunction with other
tests of hepatic damage or dysfunction.
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