Extract
1Zentrum für Kinderheilkunde und Jugendmedizin, Albert-Ludwigs-Universität, Freiburg und 2Kinderklinik, Kliniken des Landkreises Lörrach, Lörrach, 3Klinik für Kinder- und Jugendheilkunde, Med. Univ. Innsbruck, Germany
Supported by an educational grant from
Introduction
Children with urea cycle disorders present with hyperammonaemia and its non-specific symptoms. Acute hyperammonaemia is a medical emergency as the developmental and neurological outcome depends on the duration of hyperammonaemic coma [1]. The longer endogenous protein catabolism continues, the more ammonia will be produced and accumulate and the greater is the risk of coma. To minimize permanent brain damage, early diagnosis and appropriate therapy is mandatory. With diagnosis of hyperammonaemia, it is essential to differentiate between urea cycle defects and other causes of encephalopathy. In Figure 1 a practicable flowchart for establishing the correct diagnosis is depicted [2]. The emergency therapy in children with inborn metabolic disorders presenting with acute hyperammonaemia includes protein restriction, high caloric nutrition using carbohydrates and (later on) lipids, and activation of alternative nitrogen pathways by administration of sodium benzoate and/or phenylbutyrate/phenylacetate. Arginine supplementation can replenish urea cycle substrates. Additionally, essential amino acids should be given. Renal replacement therapy is indicated in cases of rising ammonia levels despite intensive therapy and has been proposed (without established evidence for this value) as an indication if ammonia levels are >400 µmol/l.
Comments