Abnormality of urine homeostasis Trimethylaminuria HP:0003614 SNOMEDCT_US:237959005 High urine trimethylamine levels Increased concentration of trimethylamine in the urine. UMLS:C0342739 Increased concentration of trimethylamine, an organic amino compound with an odor characterized as that of rotting fish, in the urine. Trimethylaminuria is generally caused by impaired oxidation of trimethylamine into the odorless compound trimethylamine N-oxide.