xanthinuria /zan′thinyo͝or′ē·ə/ [Gk, xanthos + ouron, urine] , 1. the presence of excessive quantities of xanthine in the urine. 2. a rare disorder of purine metabolism, resulting in the excretion of large amounts of xanthine in the urine because of the absence of an enzyme, xanthine oxidase, that is necessary in xanthine metabolism. This inherited deficiency may cause the development of kidney stones made of xanthine precipitate.
