Short answer · Medically reviewed summary · Last updated: 2026-05-08
Trimethylaminuria is officially classified under the ICD-10 coding system as E88.89 (Other specified metabolic disorders). While the older ICD-9 coding system utilized 277.8 (Other specified disorders of metabolism), medical providers now exclusively use the ICD-10 or the updated ICD-11 (5C51.Y) for clinical documentation and insurance billing purposes. What is the clinical classification of Trimethylaminuria? Trimethylaminuria, often referred to as "fish odor syndrome," is a rare metabolic disorder characterized by the body's inability to oxidize trimethylamine, a compound produced during the digestion of certain foods.
ICD10 code of Trimethylaminuria and ICD9 code
ICD-10 and ICD-9 codes for Trimethylaminuria, with classification details for clinicians, coders and patients.
Trimethylaminuria is officially classified under the ICD-10 coding system as E88.89 (Other specified metabolic disorders). While the older ICD-9 coding system utilized 277.8 (Other specified disorders of metabolism), medical providers now exclusively use the ICD-10 or the updated ICD-11 (5C51.Y) for clinical documentation and insurance billing purposes.
What is the clinical classification of Trimethylaminuria?
Trimethylaminuria, often referred to as "fish odor syndrome," is a rare metabolic disorder characterized by the body's inability to oxidize trimethylamine, a compound produced during the digestion of certain foods. Because Trimethylaminuria is a metabolic condition, it is categorized within broader metabolic disorder codes in standard diagnostic manuals used by clinicians globally.
How does Trimethylaminuria affect the body?
Individuals with Trimethylaminuria lack sufficient activity of the enzyme flavin-containing monooxygenase 3 (FMO3). When this enzyme is deficient, the body cannot break down trimethylamine, leading to its accumulation and subsequent release through sweat, urine, and breath. The 34 members of our DiseaseMaps community who live with Trimethylaminuria often report that the resulting odor can cause significant social and psychological distress, highlighting the need for both clinical management and emotional support.
Is Trimethylaminuria hereditary?
Yes, Trimethylaminuria is typically inherited in an autosomal recessive pattern, meaning an individual must inherit two copies of a mutated FMO3 gene (one from each parent) to manifest the primary form of the condition. Genetic testing is the gold standard for confirming the diagnosis, as specific mutations can influence the severity of the metabolic impairment.
Diagnostic and management considerations for Trimethylaminuria
- Biochemical testing: Measurement of the trimethylamine to trimethylamine N-oxide ratio in urine.
- Dietary management: Reducing intake of choline-rich foods like eggs, organ meats, legumes, and certain fish.
- Clinical monitoring: Use of specific antibiotics or supplements, such as riboflavin, under medical supervision to manage symptoms.
- Psychosocial support: Therapy to address the isolation often felt by patients with Trimethylaminuria.
Next steps
- Consult with a metabolic specialist or a geneticist to discuss diagnostic testing and potential FMO3 gene mutations.
- Connect with others who understand your experience by joining the Trimethylaminuria group on DiseaseMaps.org.
- Work with a registered dietitian specializing in metabolic disorders to create a manageable nutritional plan.
Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Trimethylaminuria.
- Orphanet: Trimethylaminuria (ORPHA:96155).
- OMIM (Online Mendelian Inheritance in Man): FMO3 Deficiency (#602079).
- National Library of Medicine: GeneReviews on Trimethylaminuria.
