Understanding Lab Tests for Trimethylaminuria
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Trimethylaminuria, commonly known as fish odor syndrome, is a rare genetic disorder that affects the body's ability to break down trimethylamine, a compound found in certain foods. This metabolic dysfunction results in the accumulation and excretion of trimethylamine through urine, sweat, and breath, creating a distinctive fishy odor that can significantly impact quality of life.
Recommended Test
TMAO (Trimethylamine N-Oxide)
This test measures trimethylamine N-oxide levels, which can be elevated in individuals with trimethylaminuria due to the body's impaired ability to properly metabolize trimethylamine. The test helps confirm the diagnosis by detecting abnormal levels of TMAO that accumulate when the normal metabolic pathway is disrupted by this genetic disorder.
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Diagnosing Trimethylaminuria
While the characteristic fishy odor may suggest trimethylaminuria, laboratory testing is essential for confirming the diagnosis. The condition is caused by deficiencies in the FMO3 enzyme, which normally converts trimethylamine to trimethylamine N-oxide (TMAO). Testing can measure these metabolites to establish a definitive diagnosis.
Understanding the Results
Elevated TMAO levels, along with clinical symptoms, can support a diagnosis of trimethylaminuria. However, interpretation of results should always be done in conjunction with a healthcare provider who can correlate laboratory findings with symptoms and family history to provide appropriate management strategies.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.
