Trimethylaminuria, also known as fish odor syndrome, is a rare genetic disorder that prevents the body from breaking down trimethylamine, a compound found in certain foods like eggs, fish, and legumes. It is caused by mutations in the FMO3 gene that result in deficiency of the flavin-containing monooxygenase 3 enzyme, which normally converts trimethylamine to odorless trimethylamine N-oxide. The TMAO (Trimethylamine N-Oxide) blood test is the most important test for diagnosing this condition.
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Trimethylaminuria is caused by mutations in the FMO3 gene that lead to deficiency or dysfunction of the flavin-containing monooxygenase 3 enzyme. This enzyme is responsible for converting trimethylamine (a compound with a strong fishy smell) into trimethylamine N-oxide, which is odorless and easily excreted by the body. When the FMO3 enzyme does not work properly, trimethylamine accumulates in the body and is released through sweat, urine, and breath, creating the characteristic fish-like odor that gives the condition its common name.
The TMAO (Trimethylamine N-Oxide) blood test is the most important test for trimethylaminuria because it measures the levels of trimethylamine N-oxide in your blood, which become abnormally elevated when your body cannot properly metabolize trimethylamine. This test helps confirm the diagnosis by detecting the metabolic dysfunction characteristic of fish odor syndrome. Some healthcare providers may also recommend genetic testing of the FMO3 gene to identify specific mutations, or a urine test that measures both trimethylamine and TMAO levels after consuming foods high in trimethylamine precursors to assess how well your body processes these compounds.
You should get tested if you or others notice a persistent fishy or foul body odor that does not improve with regular bathing and hygiene practices. Testing is particularly important if the odor worsens after eating certain foods like fish, eggs, legumes, liver, or foods containing choline and carnitine, or if you have a family history of fish odor syndrome. You should also consider testing if the odor is causing significant social anxiety, depression, or affecting your quality of life and relationships, as early diagnosis can help you manage the condition through dietary modifications and other strategies.
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What this means
Your testosterone levels are slightly below the optimal range. While this is not necessarily cause for concern, it may contribute to occasional fatigue, reduced motivation, or lower muscle mass over time.
Recommended actions
Increase resistance or strength training
Prioritize 7–8 hours of quality sleep per night, try to reduce stress
Include more zinc- and magnesium-rich foods (like shellfish, beef, pumpkin seeds, spinach)
Consider retesting in 3–6 months
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