瓜氨酸血症（Citrullinemia）是一种遗传的障碍，使得血液内积聚氨及其他有毒物质。瓜氨酸血症属于一类遗传病，称为尿素循环代谢障碍。尿素循环是一连串的在肝脏内的化学反应，包括处理因身体使用蛋白质而产生过多的氮，制造尿素，并由肾脏排出体外。

瓜氨酸血症有两种不同的种类，各自有着不同的征状，且由不同的基因突变所引起。两个种类都是由染色体隐性遗传的。由于基因的突变，使得在尿素循环中的一些酶出现缺乏，而令血液内的瓜氨酸水平上升，所以此症被称为瓜氨酸血症。

Citrullinemia is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood. Since the substances also accumulate in the urine, the disorder can also be called citrullinuria.

Two forms of citrullinemia have been described, both having different signs and symptoms, and are caused by mutations in different genes. Citrullinemia belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of chemical reactions taking place in the liver. These reactions process excess nitrogen, generated when protein is used for energy by the body, to make urea, which is excreted by the kidneys.