Hyperammonemia ICD-10-CM Codes

Read this short guide and learn about hyperammonemia ICD codes you can use.

By Telita Montales on Aug 8, 2025.

Fact Checked by RJ Gumban.

What hyperammonemia ICD codes can I use?

If you’re looking for hyperammonemia ICD codes to use, we’d like you to know that only one explicitly mentions hyperammonemia in its name. The rest are tied to specific ICD codes for metabolism-related problems, especially the urea cycle. Here are the ICD-10 codes that you can use for hyperammonemia:

E72.20 - Disorder of urea cycle metabolism, unspecified

This ICD code is meant to be used on a patient confirmed to be dealing with a disorder of the urea cycle metabolism, but it’s not specified as to what that is. Hyperammonemia is related to the urea cycle, so that you can use it.

E72.29 - Other disorders of urea cycle metabolism

This ICD code is meant to be used on a patient diagnosed with a disorder of the urea cycle metabolism. It’s best to use this for the kinds that do not have a specific ICD code, like hyperammonemia.

E72.3 - Disorders of lysine and hydroxylysine metabolism

This ICD code is meant to be used on a patient confirmed to have a lysine and hydroxylysine metabolism disorder. If you’re wondering what this has to do with hyperammonemia, this code may be used for periodic hyperlysinemia, which can be accompanied by hyperammonemia.

E72.4 - Disorders of ornithine metabolism

This ICD code is meant to be used on a patient confirmed to have a disorder of the ornithine metabolism. Hyperammonemia is related to this.

P74.6 - Transitory hyperammonemia of newborn

This ICD code is meant to be used on a newborn patient confirmed to have transitory hyperammonemia.

Are these hyperammonemia ICD codes billable?

Yes. All of the aforementioned hyperammonemia-related ICD codes are valid and billable.

Clinical information about hyperammonemia:

Hyperammonemia is the term that healthcare professionals use to refer to the state of having too much ammonia in the bloodstream. Having too much of this is not good because it is toxic. Our intestines produce ammonia after processing protein. Ammonia travels from the liver and then gets eliminated via the urea cycle (hence the urea cycle ICD codes above).

If the liver and the urea cycle function fine, you don’t have to worry about this problem. Still, if they have issues with their operations, they might not do their job of getting rid of ammonia, causing ammonia to build up over time. This needs to be addressed immediately because it can become life-threatening.

People with hyperammonemia will likely have the following symptoms:

They will have headaches
They will feel dizzy, nauseous, and may even vomit
They will have difficulty balancing and coordinating themselves
They will have trouble with speech
They might become irritable and may undergo mood and behavioral changes
In extreme cases, they might start hyperventilating and may have seizures
They might lapse into a coma

Synonyms include:

Hyperammonemia
Hyperammonemic encephalopathy
Hyperammonemic encephalopathy due to carbonic anhydrase VA deficiency
Hyperinsulinism and hyperammonemia syndrome
Periodic hyperlysinemia with hyperammonemia
Hyperammonemia, type III
Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome
Transient hyperammonemia in infancy

Commonly asked questions

Apart from Item 5 above, no other ICD codes specify hyperammonemia in their names.

Healthcare professionals will count the ammonia amounts in the blood via a blood test. They may also ask for urine samples from the patient. Hyperammonemia can cause damage to the brain, so they might also conduct imaging tests to check for any damage.

That depends. Hyperammonemia is a symptom of a much larger problem, so whatever is causing the hyperammonemia needs to be addressed. In terms of managing it, making lifestyle changes helps. Changes can include a diet that doesn’t contain trans fats or high fructose, avoiding alcohol, avoiding red meat, and taking required medication as instructed (nothing more, nothing less).

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