Affected people have unusually high concentrations of xanthine in their blood and urine, which can lead to health problems such as renal failure and xanthine kidney stones, one of the rarest types of kidney stones.[citation needed]
Kojima T.; Nishina T.; Kitamura M.; Hosoya T.; Nishioka K. (1984). "Biochemical studies on the purine metabolism of four cases with hereditary xanthinuria". Clin Chim Acta. 137 (2): 189–98. doi:10.1016/0009-8981(84)90179-7. PMID6423323.