Overview of the condition

Trimethylaminuria (TMAU), commonly referred to as fish odor syndrome, is a metabolic disorder characterized by the excessive excretion of trimethylamine (TMA) in bodily fluids, such as urine, sweat, and breath. This condition arises from genetic variations affecting the enzyme flavin-containing monooxygenase 3 (FMO3), which plays a crucial role in the oxidation of TMA to its non-odorous metabolite, trimethylamine N-oxide (TMAO), primarily in the liver.

The severity of TMAU symptoms can vary widely among affected individuals, ranging from mild to severe malodor, often leading to significant psychosocial distress and impaired quality of life. Diagnosis typically involves clinical evaluation, including patient history, odor characterization, and laboratory tests to measure TMA levels in urine.

Individuals with TMAU may experience exacerbation of symptoms after consuming foods rich in precursors of TMA, such as choline, lecithin, and trimethylamine-N-oxide-containing substances found in seafood, eggs, and certain vegetables. The ingestion of these dietary components leads to increased TMA production by gut bacteria, exacerbating the characteristic malodor associated with TMAU.

The distinctive malodor associated with TMAU is often described as resembling that of decaying fish or rotten eggs. This odor emanates from the accumulation of TMA and its subsequent release through excretory pathways, contributing to the social stigmatization and psychological burden experienced by affected individuals.

Management strategies for TMAU primarily focus on dietary modifications aimed at reducing the intake of TMA precursors, as well as the use of antibiotics to suppress the production of TMA by gut bacteria. Additionally, supportive measures such as counseling and psychological support may help individuals cope with the psychosocial impact of the condition.

Last updated : March 2024