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Ammonia

Ammonia

Synonyms - Specimen - Reference Value - Method - Description - Indications - Interpretation

Synonyms : NH3 
Specimen   : Plasma collected in completely filled ( heparin ) tube .Specimen should be transported tightly capped and in an ice slurry . 
Reference Value : Adults 19 - 60 micron g/dL 
Method : spectrophotometry 
Description 
Blood ammonia ( NH3 ) comes from two sources 
a - Deamination of amino acids during protein metabolism.
b - Degradation of proteins by colon bacteria .

The liver converts ammonia in the portal blood to urea , which is excreted by kidneys . When liver function is severely compromised , especially in situations in which decreased hepatocellular  function is combined with impaired portal blood flow , ammonia levels rise .
Ammonia is potentially toxic to the central nervous system 

Indications
 - Evaluated advanced liver disease 
- Identify impending hepatic encephalopathy with known liver disease 

Interpretation 

Increased in 

1 - Gastrointestinal hemorrhage 
2- Genitourinary tract infection with distention and stasis ( urea-splitting urinary tract infection ) 
3 - Urea cycle metabolism defects 
4 - Hepatic coma 
5 - Liver failure , late cirrhosis 
6 - Total parenteral nutrition 
7 - Portacaval shunting 



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