Schematic representation of the major sources of ammonia ...

Schematic representation of the major sources of ammonia production and its excretory pathway (GI = gastrointestinal, IMV = inferior mesenteric vein). 

The key is that although hepatic causes (namely, the many causes of decompensated liver disease) are the most common, there are also many non-hepatic causes. They can be grouped into increased production of ammonia and decreased metabolism. 

= Non hepatic causes of hyperammonemia =

Impaired elimination of ammonia:

 - Inherited Urea Cycle Disorders

 - Portosystemic shunts

 - Urinary diversion – ureterosigmoidostomy, ileal conduit

 - Medications

   - Valproic acid

   - Chemotherapy agents – 5FU, asparaginase

Excess (production) of ammonia:

 - Urease producing UTI (i.e proteus)

 - Multiple myeloma, CML, AML

 - Large GI bleed

 - Significant endogenous dietary protein

Other (rare):

 - Reye syndrome (Peds)

 - Primary carnitine deficiency

#Ammonia #Pathophysiology #Hyperammonemia #Differential #Diagnosis
Contributed by

Dr. Gerald Diaz
Board Certified Internal Medicine Hospitalist, GrepMed Editor in Chief 🇵🇭 🇺🇸 - Sign up for an account to like, bookmark and upload images to contribute to our community platform. Follow us on IG: | Twitter:

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