Hyperammonemia is a typical symptom of urea cycle disorders. While early-onset argininosuccinic aciduria (ASA) can often be detected by hyperammonemia, patients with late-onset ASA predominantly present with psychomotor retardation and mental disorders. However, in late-onset ASA that develops during early childhood, hyperammonemia can sometimes be caused by acute infections, stress, and reduced dietary intake. Here, we report the case of a 14-year-old boy with late-onset ASA associated with hyperammonemia that was triggered by an influenza A infection. Due to the infection, he presented with a fever and was unable to eat food or take oral medication. He then experienced restlessness, a disturbance in his level of consciousness, and seizures. Hyperammonemia (3286 μg/dL, reference value ≤100 μg/dL) was detected. He was biochemically diagnosed with ASA based on increased serum and urinary argininosuccinic acid levels. Additionally, genetic testing revealed compound heterozygous mutations in the ASL gene: c.91G > A(p.Asp31Asn) and c.1251-1G > C. This case revealed that in late-onset ASA, hyperammonemia can occur not only in early childhood but also during adolescence. Late-onset ASA may have a very broad clinical spectrum that includes hyperammonemia. We suggest that urea cycle disorders such as ASA must be considered when patients present with hyperammonemic decompensation during adolescence.

高氨血症是尿素循环紊乱的典型症状。高氨血症常可检测出早发性精氨酸琥珀酸尿症（ASA），而晚发性ASA患者则主要表现为精神运动障碍和精神障碍。但是，在儿童早期发展的晚期ASA中，高氨血症有时可能是由急性感染，压力和饮食摄入减少引起的。在这里，我们报道了一名14岁男孩，患有甲型流感感染引发的高氨血症伴发迟发性ASA的病例。由于感染，他发烧，无法进食或服用口服药物。然后他经历了躁动不安，意识障碍和癫痫发作。检测到高氨血症（3286μg/ dL，参考值≤100μg/ dL）。根据血清和尿中精氨酸琥珀酸水平的升高，他被生化诊断为ASA。此外，基因测试还揭示了棉铃虫中的复合杂合突变。ASL基因：c.91G> A（p.Asp31Asn）和c.1251-1G>C。此病例表明，在发病较晚的ASA中，高氨血症不仅可以在儿童早期发生，而且可以在青春期发生。迟发性ASA可能具有非常广泛的临床范围，包括高氨血症。我们建议，当患者在青春期出现高氨血症代偿失调时，必须考虑尿素循环障碍，例如ASA。