patients must be individualized, in spite of the
availability of drugs that enhance waste nitrogen loss.
Outcomes
UCDs are marked by an accumulation of glutamine in
astrocytes, as well as astrocyte oedema and dysfunction
with resulting encephalopathy (Norenberg et al
2005). The neurological outcome of patients with
UCDs depends on many factors, including the age at
diagnosis, the degree of enzyme impairment, the time
when diet therapy is initiated, and the number,
duration, and severity of hyperammonaemic episodes,
although the predictive value of some of these factors
is uncertain (Nicolaides et al 2002). The relationship
between elevated plasma concentrations of ammonia
and glutamine with poor neurological outcome is well
known, as discussed by Gropman and colleagues
elsewhere in this issue.
Hyperammonaemia