Beyond the Odour: Enhancing Primary Care for Trimethylaminuria Patients

Para além do odor: Aprimorando os Cuidados Primários para doentes com Trimetilaminúria

Abstract

Trimethylaminuria (TMAU) is a rare, socially debilitating metabolic disorder, caused by an enzyme deficiency due to mutations in the flavin-containing mono-oxygenase 3 (FMO3) gene, resulting in excess excretion of trimethylamine in body fluids. Nevertheless, it may also occur due to a low processing capacity of the enzyme. TMAU is characterized by body odour that resembles rotting fish which can be intermittent, variable and influenced by diet, menstruation and medications.

A literary review of articles containing the keywords “trimethylaminuria” and “fish odour syndrome”, published between 2000 and 2024 in Portuguese, English and Spanish, was performed.

Diagnosis of trimethylaminuria is made by a combination of clinical, biochemical and genetic tests. It is also important to exclude other causes of fish odour, such as poor hygiene, gingivitis, bacterial vaginosis, urinary tract infections, chronic and advanced liver and kidney disease. Even though there are currently no effective treatments, patients may use products such as chlorophyllin and activated charcoal, riboflavin supplements and antibiotics. In addition, patients are advised to avoid foods such as shellfish, eggs, meat, certain vegetables, and mushrooms, which contain TMA precursors. These measures only temporarily reduce the bad smell, and more studies are being conducted to resolve these symptoms.

The psychosocial impact of trimethylaminuria is profound, often leading to low self-esteem, isolation, anxiety, depression and eventually suicidal thoughts. Patients may develop obsessive–compulsive behaviors to mitigate the unpleasant odour. Further research is required to improve diagnostic and treatment options, as well as enhance patients' quality of life.