What is a reddish urinary pigment, considered as the substance which gives to the urine of rheumatism its characteristic color. It also causes the red color often seen in deposits of urates called?

uroerythrin — A reddish urinary pigment, considered as the substance which gives to the urine of rheumatism its characteristic color. It also causes the red color often seen in deposits of urates. (Webster's 1913.)