TMAO (Trimethylamine N-Oxide) blood Biomarker Testing
A TMAO test measures a gut microbe–linked metabolite tied to cardiometabolic risk, with convenient Quest lab draws and PocketMD guidance via Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
TMAO (trimethylamine N-oxide) is a small molecule your body makes after gut bacteria break down certain nutrients from food. Your liver converts those breakdown products into TMAO, which then circulates in your blood and is cleared largely by your kidneys.
A TMAO test does not diagnose heart disease or a gut condition on its own. Instead, it gives you one more data point about diet–microbiome metabolism and how that pattern may relate to cardiometabolic risk, especially when you interpret it alongside cholesterol, inflammation markers, blood sugar, and kidney function.
Because TMAO can change with recent meals, supplements, kidney function, and even antibiotic use, the most useful way to use this test is to interpret your result in context and, when appropriate, trend it over time after a consistent routine.
Do I need a TMAO (Trimethylamine N-Oxide) test?
You might consider a TMAO test if you are trying to understand your cardiometabolic risk beyond standard labs, especially when your family history, blood pressure, cholesterol, or blood sugar suggests you should pay closer attention. TMAO is not a replacement for those core markers, but it can add insight into how your gut microbiome and diet pattern may be interacting with your risk profile.
This test can also be reasonable if you are making targeted changes—such as shifting protein sources, adjusting choline/carnitine intake, or working on kidney health—and you want an objective way to see whether your internal chemistry is moving in the direction you expect.
You may want to hold off on testing (or interpret cautiously) if you have known kidney disease, a recent infection treated with antibiotics, or a major diet change in the last couple of weeks, because those factors can strongly influence TMAO. If you are pregnant or managing multiple chronic conditions, it is especially important to review results with your clinician.
Testing is most helpful when it supports clinician-directed care and a clear follow-up plan, rather than trying to self-diagnose from a single number.
TMAO is measured in a CLIA-certified laboratory; results are for health education and risk discussion and are not a standalone diagnosis.
Lab testing
Order a TMAO test and choose a Quest draw location
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
Vitals Vault lets you order a TMAO blood test without needing to coordinate a separate lab requisition visit. You can choose a nearby Quest draw location, complete the blood draw, and then review your result in a format designed for real-world next steps.
If your result is outside the lab’s reference interval—or it is “in range” but doesn’t match your goals—PocketMD can help you make sense of what commonly drives TMAO up or down and which companion labs are worth checking so you are not guessing.
Because TMAO is sensitive to diet and kidney clearance, many people benefit from repeating the test after they standardize a few variables (for example, consistent diet for several days and stable supplement use). Vitals Vault makes it straightforward to re-order and trend your results over time.
- Order online and draw at a Quest location
- PocketMD helps you interpret results in context
- Easy re-testing to track changes over time
Key benefits of TMAO testing
- Adds a gut microbiome–linked data point to your cardiometabolic risk picture.
- Helps you see whether recent diet patterns (especially certain animal foods) may be shifting your metabolism.
- Supports more informed conversations about risk when standard cholesterol results feel incomplete.
- Can highlight when kidney clearance may be influencing metabolite buildup, prompting a look at kidney markers.
- Gives you a measurable way to evaluate lifestyle changes instead of relying on symptoms alone.
- Pairs well with inflammation, lipid, and glucose markers to interpret risk as a pattern rather than a single number.
- Makes trending easier when you use consistent prep and review results with PocketMD.
What is TMAO (Trimethylamine N-oxide)?
TMAO (trimethylamine N-oxide) is a metabolite made through a two-step process. First, gut bacteria convert certain dietary nutrients—most notably choline, phosphatidylcholine (lecithin), and carnitine—into trimethylamine (TMA). Then your liver oxidizes TMA into TMAO, which circulates in your bloodstream.
Researchers study TMAO because higher levels have been associated in some populations with higher rates of cardiovascular events and other cardiometabolic outcomes. The relationship is not simple cause-and-effect for every person, and your result should be interpreted alongside your overall risk factors, kidney function, and diet.
TMAO is also strongly influenced by kidney clearance. If your kidneys filter less efficiently, TMAO can rise even if your diet and microbiome are unchanged. That is one reason TMAO is best interpreted with creatinine and estimated glomerular filtration rate (eGFR).
Food sources matter, but timing matters too. Fish and seafood can raise TMAO directly because they contain preformed TMAO, which can temporarily elevate blood levels after a meal. That makes pre-test preparation and consistent retesting conditions important if you want to compare results over time.
How TMAO fits into heart and metabolic health
TMAO is often discussed as a “diet–microbiome–host” marker: it reflects what you eat, how your gut microbes process it, and how your liver and kidneys handle the byproducts. In practice, it is most useful as a contextual marker—one that may help explain why two people with similar cholesterol numbers can have different risk profiles or respond differently to the same diet.
Why one result is rarely the whole story
A single TMAO value can be skewed by recent seafood intake, changes in gut bacteria after antibiotics, or reduced kidney filtration. If you are using TMAO to guide decisions, you usually get better signal by standardizing prep (including diet) and pairing the result with lipids, inflammation markers, and kidney function tests.
What do my TMAO (Trimethylamine N-oxide) results mean?
Low TMAO levels
A low TMAO result is commonly seen in people who eat little to no seafood and fewer choline/carnitine-rich animal foods, or whose gut microbiome produces less TMA from those nutrients. In many contexts, lower TMAO is considered a favorable finding, but it is not a guarantee of low cardiovascular risk. If you have symptoms or risk factors, your clinician will still focus on core markers like LDL-related measures, blood pressure, glucose, and inflammation.
Optimal (in-range) TMAO levels
An in-range result suggests your current diet–microbiome metabolism and kidney clearance are producing a TMAO level that falls within the lab’s expected interval. This is most meaningful when it matches stable kidney function and a consistent pre-test routine. If you are tracking changes, try to repeat the test under similar conditions so you are comparing like with like.
High TMAO levels
A high TMAO result can reflect recent seafood intake, higher intake of certain animal-based nutrients (choline/carnitine), a microbiome pattern that produces more TMA, reduced kidney clearance, or a combination of these. It does not diagnose heart disease, but it can be a useful prompt to review your overall cardiometabolic risk profile and kidney markers. If the result is unexpected, repeating the test after avoiding seafood for a couple of days and keeping your diet consistent can help clarify whether the elevation is persistent.
Factors that influence TMAO
Diet is a major driver: fish/seafood can raise TMAO directly, while choline- and carnitine-rich foods can raise TMAO indirectly through gut bacteria. Kidney function matters because TMAO is cleared in urine, so reduced eGFR can raise levels independent of diet. Antibiotics, probiotics, and major dietary shifts can change the gut microbiome and alter TMA production. Timing also matters—your result may differ depending on whether the sample was fasting and what you ate in the day or two before the draw.
What’s included
- Tmao (Trimethylamine N Oxide)
Frequently Asked Questions
Do I need to fast for a TMAO blood test?
Fasting requirements can vary by lab, but fasting (or at least keeping your pre-test routine consistent) can make results easier to compare over time. Because seafood can raise TMAO directly, avoiding fish and shellfish for 24–48 hours before the draw is a common strategy when you want a baseline-style reading. Follow the instructions on your order, and if you are trending results, repeat the same prep each time.
What is a normal TMAO level?
“Normal” depends on the lab method and the reference interval printed on your report, so the best interpretation starts with your lab’s range. In general, lower values are often viewed as more favorable in cardiometabolic risk research, but your personal risk depends on the full picture—lipids, blood pressure, glucose control, inflammation, kidney function, and lifestyle.
Can kidney problems raise TMAO?
Yes. TMAO is cleared largely by the kidneys, so reduced kidney filtration can raise blood levels even if your diet and microbiome are unchanged. If your TMAO is high, it is reasonable to review creatinine and eGFR (and sometimes urine markers) with your clinician to understand whether clearance is part of the story.
Does eating fish increase TMAO?
Often, yes. Fish and some seafood contain preformed TMAO, which can temporarily increase blood levels after you eat it. That does not automatically mean fish is “bad” for you; it means TMAO is sensitive to recent intake, so timing and consistency matter when you test.
How often should I retest TMAO?
If you are using TMAO to track a change (diet pattern, weight loss plan, kidney health workup, or microbiome-targeted approach), retesting after about 6–12 weeks is a common interval. Retesting sooner can be useful if you suspect your first result was influenced by a recent meal, antibiotics, or an unusual week of eating. The best schedule depends on what you are trying to learn and what other labs you are monitoring.
What other tests should I consider with TMAO?
TMAO is most informative when paired with cardiometabolic and kidney context. Many people review it alongside a lipid profile (and, when available, ApoB), inflammation markers such as hs-CRP, glucose markers such as fasting glucose and HbA1c, and kidney function markers such as creatinine and eGFR. PocketMD can help you choose companion labs based on your goals and your current results.