Plasma glutamine and ammonia concentrations in ornithine carbamoyltransferase deficiency and citrullinaemia

A retrospective review of the plasma ammonia and glutamine concentrations d uring the long-term management of 7 patients with ornithine carbamoyltransf erase (OCT) deficiency and three with citrullinaemia is presented. The rela tionship between the plasma concentrations of ammonia and glutamine is not a simple linear one and there are significant differences between the two d isorders. Patients with citrullinaemia tend to have higher plasma ammonia c oncentrations for a given plasma glutamine concentration compared to those with OCT deficiency. The possible reasons for these differences and the imp lications for management are discussed.