Acute hyperammonemia without signs of common causes in the elderly might be challenging to identify. We report the oldest case known to date of a female patient with late onset ornithine carbamyltransferase deficiency (OTC), which was unmasked after a protein overload due to nutritional supplements. Our case illustrates how environmental factors (protein overload) in previously unknown OTC in the elderly leads to hyperammonemic encephalopathy and highlights that early treatment prevents persisting neurological deficits and should be considered in absence of common causes of hyperammonemic encephalopathy. A 68-year-old woman presented with acute confusion, which progressed into a deep coma (Glasgow-Coma-Scale score 3) within a few hours. The only remarkable finding was a plasma ammonia (NH3) concentration of 697 μmmol/l (range 12–47 μmmol/). Third party history revealed that the patient disliked meat for most of her life (meat = protein, which needs to be metabolized) and had taken nutritional supplements (since supplements often have a high protein-ratio) 2 days before the symptoms started. Protein catabolism results in NH3, which is metabolized via the urea cycle. Consequently, the acute hyperammonemia in our patient was thought to be related to an inherited metabolic disorder, which only unmasked itself as a result of an overload of the corresponding metabolite (in this case protein). Since ornithine carbamyltransferase deficiency (OTC) is the most common inherited urea cycle disorder, this diagnosis became likely and was confirmed later via genetic and metabolic testing (amino acids, orotic acid, etc.). After 2 weeks of treatment (dialysis, low-protein-diet, nitrogen-lowering medication) the patient was discharged in a healthy condition without any neurological deficits. OTC is a x-chromosomal linked disorder, that usually manifests in newborn infants and children, but also rarely in adults and even rarer in the elderly (50- till 60-years-old), where it is probably underdiagnosed. In case of hyperammonemic encephalopathy – regardless of the underlying cause -, treatment should be started early to prevent persisting neurological deficits. OTC should be considered in absence of common causes of hyperammonemic encephalopathy.

中文翻译：

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氨和昏迷–一名68岁女性迟发性半合鸟氨酸鸟氨酸氨基甲酰转移酶缺乏症的病例报告

没有老年人常见原因的急性高氨血症可能难以识别。我们报告了迄今已知的最古老的病例，该患者患有晚发病的鸟氨酸鸟氨酸氨基甲酰转移酶缺乏症（OTC），由于营养补给导致蛋白质超载后，该病未被发现。我们的案例说明了老年人中以前未知的OTC中的环境因素（蛋白质超载）如何导致高氨血症性脑病，并强调了早期治疗可防止持续的神经功能缺损，在没有高氨血症性脑病的常见原因的情况下应予以考虑。一名68岁的妇女表现出急性意识混乱，在数小时内发展为深度昏迷（格拉斯哥-科马氏评分3分）。唯一的显着发现是血浆氨（NH3）浓度为697μmmol/ l（范围12-47μmmol/）。第三方的历史记录显示，患者一生中大部分时间都不喜欢吃肉（肉=蛋白质，需要代谢），并且在症状出现前2天服用了营养补品（因为补品通常具有较高的蛋白质比例）。蛋白质分解代谢产生NH3，NH3通过尿素循环代谢。因此，我们患者的急性高氨血症被认为与遗传性代谢紊乱有关，这种代谢紊乱只是由于相应代谢产物（在这种情况下为蛋白质）超负荷而无法掩盖。由于鸟氨酸氨基甲酰基转移酶缺乏症（OTC）是最常见的遗传性尿素循环疾病，因此这种诊断成为可能，后来通过遗传和代谢测试（氨基酸，乳清酸等）得到证实。治疗2周后（透析，低蛋白饮食，降氮药物）患者出院后处于健康状态，无任何神经功能缺损。OTC是一种x染色体连锁疾病，通常表现在新生婴儿和儿童中，但在成年人中很少见，在老年人（50至60岁）中则很少见，这种情况可能未得到充分诊断。如果发生高氨血症性脑病，无论其潜在原因是什么，都应及早开始治疗，以防止持续的神经功能缺损。在没有高氨血症性脑病常见原因的情况下应考虑使用OTC。可能未得到充分诊断的地方。如果发生高氨血症性脑病，无论其潜在原因是什么，都应及早开始治疗，以防止持续的神经功能缺损。在没有高氨血症性脑病常见原因的情况下应考虑使用OTC。可能未得到充分诊断的地方。如果发生高氨血症性脑病，无论其潜在原因是什么，都应及早开始治疗，以防止持续的神经功能缺损。在没有高氨血症性脑病常见原因的情况下应考虑使用OTC。