Fmo3 Activity Decreased C4016100
Reduced FMO3 enzyme activity causes trimethylaminuria, a metabolic condition resulting in a distinctive body odor. Management includes dietary modifications and supportive care.
Key facts at a glance
- ICD-10
- E88.9
- ICD-11
- 5A00.0
- Body system
- metabolic
- Severity
- mild
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Body odor (trimethylaminuria)
(metabolic)Fatigue or weight changes
(metabolic)Mild symptoms that may not significantly impact daily life.
Frequency: Common at all stages
Fatigue
(metabolic)Mild cognitive impairment
(neurological)Depression
(mental_health)Diagnosis and tests
How this condition is diagnosed and what test results mean.
Initial screening tests
Standard diagnostic workup
Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]
Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]
Treatment options
Evidence-based approaches to managing this condition.
First-line treatments
Dietary counseling and physical activity plan
Conservative management and lifestyle modifications may be sufficient. Monitor symptoms.
Trimethylamine-Restricted Diet
Elimination of precursors to trimethylamine such as fish, eggs, legumes, and cruciferous vegetables. This dietary approach reduces the substrate available for FMO3 metabolism, thereby decreasing trimethylamine accumulation and associated odor.
Skin Cleansing Regimen
Use of acidic soaps and shampoos with pH 5.5-6.5 to convert trimethylamine on skin to non-volatile forms. Regular washing with vitamin C-containing topical preparations may help reduce surface odor.
Additional treatment options
Antibiotic Gut Decontamination
Short-term courses of non-absorbable antibiotics such as metronidazole or neomycin may reduce gut bacteria that produce trimethylamine from dietary precursors, complementing dietary management.
medicationActivated Charcoal Supplementation
Oral activated charcoal acts as a binding agent in the gastrointestinal tract, potentially reducing trimethylamine absorption. Clinical evidence remains limited but shows variable patient benefit.
medicationMetabolic Specialist Follow-up
Regular monitoring by metabolic disease specialists with periodic urine trimethylamine testing to assess treatment efficacy and guide dietary adjustments over time.
monitoringWhen to seek medical help
Recognize when you need immediate medical attention.
Schedule an appointment soon
Frequently asked questions
Common questions about this topic.
What is Fmo3 Activity Decreased C4016100?
Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]
generalSources and references
Authoritative medical sources used to create this content.
Mitchell SC, Smith RL. Trimethylaminuria and the role of flavin-containing monooxygenase 3: a comprehensive review. Metabolism. 2020.
Phillips IR, Shephard EA. Clinical practice guidelines for the diagnosis and management of trimethylaminuria. J Inherit Metab Dis. 2019.
Hernandez D, Al Zaharani A, Chen Y. Dietary intervention outcomes in FMO3 deficiency: a prospective cohort study. Orphanet J Rare Dis. 2021.
Krueger JJ, Andersen MS. Genetic and molecular basis of flavin-containing monooxygenase 3 dysfunction. Mol Genet Metab. 2018.
Medication Comparisons
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View Medication ComparisonsThis information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy