The short answer
A gut-microbiome metabolite linked to cardiovascular risk — produced when gut bacteria break down choline and carnitine from red meat, eggs and dairy, measured from a standard blood draw. At TestWell it costs $44.99 plus a $6 lab processing fee, requires an 8–12 hour fast, and results post in 3–5 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest.
TestWell Price
$44.99
+ $6 lab processing fee
Trimethylamine N-oxide is formed when gut bacteria metabolize dietary choline and L-carnitine into trimethylamine, which the liver then oxidizes to TMAO. Higher circulating TMAO has been associated with increased risk of heart attack, stroke and kidney disease in several large cohorts, independent of traditional risk factors, and it is one of the few blood markers that reflects the interaction between diet and the gut microbiome. Levels respond to dietary change within weeks, which makes TMAO useful for tracking the effect of reducing red meat or adjusting the diet. Kidney function affects clearance, so results are read alongside creatinine and cystatin C.
Sample Type
Blood draw
Fasting
Required
Results In
3–5 business days
Performed At
Quest
Your TMAO (Trimethylamine N-Oxide) results will include values for each of the 1 biomarker tested, along with reference ranges. Results are reviewed by a licensed physician before being released to your secure portal.
If any values fall outside the normal range, your report will include guidance on what that may mean and recommended next steps. You'll receive an email notification when your results are ready, typically within 3–5 business days.
Typical reference range layout
Lab reports show where your value sits relative to established reference intervals—your physician interprets this in context for you. Already have results? Analyze them with your AI assistant against our physician-reviewed ranges.
Fast for 8–12 hours (water only). Avoid fish and seafood for 24 hours before the draw — they can transiently raise TMAO.
TestWell orders the same TMAO (Trimethylamine N-Oxide) the labs run for doctors' offices, so you can walk into Quest Diagnostics with our requisition — no doctor's visit, a licensed physician authorizes the order, and most patient service centers take walk-ins. The table shows each lab's own test code, the name printed on the requisition, what the lab charges on its own consumer site, and the price through TestWell at that lab (plus one $6 fee per order).
| Lab | Test code | On the requisition | Lab's own site | Through TestWell |
|---|---|---|---|---|
| Quest Diagnostics | test code 94154 | “TMAO (Trimethylamine N-Oxide)” | not sold direct | $44.99 + $6 |
You choose the lab at checkout; the requisition is written for that lab and arrives by email within minutes. New York and New Jersey orders draw at BioReference. Lab-direct prices are read from the labs' public pages and re-checked regularly.
Where to get it near you: patient service centers by state and city · search by ZIP code
A TMAO (Trimethylamine N-Oxide) test costs $44.99 at TestWell — $50.99 all-in, since the $6 lab processing fee is charged once per order and there is no draw or physician fee. Hospital outpatient labs typically bill around $180.00 self-pay. With insurance you pay your plan's negotiated rate against your deductible; TestWell's price is fixed before the draw and HSA/FSA-eligible.
| Where you order | Price | One test, all-in | Notes |
|---|---|---|---|
| TestWell (drawn at Quest) | $44.99 | $50.99 | Includes the one $6 lab processing fee, charged once per order |
| Hospital outpatient lab, self-pay (typical) | $180.00 | $180.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Lab test codes: Quest test code 94154. Competitor prices are read from the linked public pages and re-checked regularly; the labs' sites may add taxes or change prices without notice.
Compare more: Quest Diagnostics price list · Labcorp price list · Quest vs Labcorp · Lab test price checker
TMAO (Trimethylamine N-Oxide) test results are typically ready in 3–5 business days after your draw at Quest. TestWell emails you the moment they post, and your results dashboard shows each marker against its reference range with a plain-English explanation.
Yes. Fast for 8–12 hours (water only). Avoid fish and seafood for 24 hours before the draw — they can transiently raise TMAO. The fasting before blood work guide covers how long to fast, what you can drink, and which results eating changes.
Order the TMAO (Trimethylamine N-Oxide) test online from TestWell for $44.99 (plus a $6 per-order lab processing fee) — no doctor's visit, referral or insurance needed. A licensed physician authorizes the order, then you walk into any Quest patient service center near you for the draw (the lab locator on our site lists the closest ones by ZIP code), and results arrive in 3–5 business days.
The TMAO (Trimethylamine N-Oxide) test is Quest Diagnostics test code 94154. TestWell orders it under that code for $44.99 at Quest — no doctor's visit or insurance required, results in 3–5 business days. Codes verified against the labs' catalogs in 2026.
TestWell Price
$44.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
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TMAO (Trimethylamine N-Oxide)
$44.99