uroerythrin

from The Century Dictionary.

• noun A red coloring matter, seldom if ever found in normal urine, but present in this fluid in fevers, especially rheumatic fever.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physiol. Chem.) 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry A red pigment (chromophore) associated with the brickdust deposit