A new method to determine urinary quinoline compounds in patients with bladder cancer.

We developed a new method to measure quinoline compounds including kynurenic acid, xanthurenic acid, and the 8-methyl ether of xanthurenic acid in the urine. The excretion of quinoline compounds in 33 patients with bladder cancer was investigated. Abnormal excretion of the 8-methyl ether of xanthurenic acid was confirmed in 13 patients. There were significant increases in the excretion of kynurenic acid and the 8-methyl ether of xanthurenic acid in males and of xanthurenic acid in females. After a L-tryptophan load, the excretion of all three derivatives was increased in males and kynurenic acid excretion was increased in females.