Providing incidence figures for secondary causes of hyperammonemia is not possible. Any severe impairment of liver function, whether temporary or permanent, can initiate onset of hepatic encephalopathy. A rapid diagnostic evaluation and alleviation of the cause must be accompanied by treatment. While the vast majority of morbidity associated with hyperammonemia derives from the primary cause, such as chronic liver disease, repeated hyperammonemic episodes also can cause morbidity. The result, given the direct toxicity of ammonia on the CNS, is a progressive decrease in intellectual function.
Animal studies suggest actual cell death as the cause.
In the genetic forms of hyperammonemia, gender distribution is equal because almost all types are autosomal recessive traits. OTC deficiency affects males predominantly, although female carriers have been clinically affected. Acquired causes are distributed randomly between sexes. However, some acquired causes, such as alcoholic cirrhosis, show a population distribution skewed by societal phenomena. Genetic causes manifest themselves under a wide variety of conditions.