Quick Facts
- Sample: Blood (serum or plasma)
- Fasting: Yes; 10–12 hours required, avoid fish/seafood 24 hours prior
- Turn-around: 3–5 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Assess cardiovascular risk through a biomarker linked to gut microbe metabolism
- Gain proactive insights beyond standard cholesterol panels for heart health monitoring
- Order easily online with no physician referral required
- Convenient local testing at thousands of lab draw centers nationwide
- Private, secure results delivered online within days for faster health decisions
- Personalize prevention with actionable data to guide diet and lifestyle changes
Who Is This Test For?
- Individuals with family history of heart disease seeking early risk assessment
- People with elevated cholesterol, diabetes, or obesity monitoring cardiovascular health
- Health-conscious adults wanting proactive heart disease screening beyond traditional tests
- Those evaluating the effectiveness of dietary changes to reduce cardiovascular risk
- Patients with metabolic or liver conditions requiring comprehensive heart health monitoring
How It Works – Just 3 Steps
- Order online — Select your test and complete checkout securely
- Visit a lab — Visit any partnering lab location for a quick blood draw
- Get results — Access confidential results in your online account within 3–5 days
FAQ
What does this test measure? It measures TMAO levels in your blood—a metabolite produced when gut bacteria digest nutrients like L-carnitine and lecithin, linked to heart disease risk.
Do I need to prepare for this test? Yes, fast for 10-12 hours and avoid all fish and seafood for 24 hours before your blood draw to ensure accurate results.
What does an elevated TMAO level mean? Elevated TMAO indicates 2-3 times higher risk of heart attack or stroke; discuss results with your healthcare provider for personalized risk assessment (Quest Diagnostics 2025).
Can I lower my TMAO levels? Yes, reducing red meat, egg yolks, and full-fat dairy intake, plus increasing physical activity and probiotics, can lower TMAO levels.
How is this different from a cholesterol test? TMAO reflects gut microbiome-related cardiovascular risk, complementing cholesterol tests by revealing additional heart disease pathways not captured by lipid panels.
More Details
What is the purpose of this test?
This test measures blood levels of Trimethylamine N-oxide (TMAO) to assess your risk of cardiovascular disease. TMAO is a metabolite produced by your liver after gut bacteria digest certain nutrients—primarily L-carnitine from red meat and lecithin from egg yolks, meats, and full-fat dairy products. Elevated TMAO levels have been strongly linked to atherosclerosis, heart attacks, and strokes (Cleveland Clinic 2016). This test uses advanced methodologies like Nuclear Magnetic Resonance (NMR) or Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) to provide precise quantification, helping you and your healthcare provider understand cardiovascular risk beyond traditional markers.
Who would benefit from this test?
This test is particularly valuable for individuals with family history of heart disease or existing cardiovascular risk factors such as high cholesterol, diabetes, obesity, or high blood pressure. It's also beneficial for health-conscious adults seeking proactive monitoring before symptoms appear. According to the American Heart Association, understanding gut microbiota-derived metabolites like TMAO provides complementary insights into heart disease pathways (AHA 2023). Anyone making dietary or lifestyle changes to reduce heart disease risk can use this test to monitor the effectiveness of their interventions.
When should I order a Trimethylamine N-oxide (TMAO) Blood Test?
Consider ordering this test if you have unexplained cardiovascular risk despite normal cholesterol levels, want baseline assessment before implementing heart-healthy lifestyle changes, or need to monitor the impact of dietary modifications. It's especially useful when traditional risk factors don't fully explain your cardiovascular profile. Individuals with these conditions should consider testing:
- Family history of early cardiovascular disease
- High cholesterol, high blood pressure, or diabetes
- Overweight or obesity
- Insulin resistance or metabolic syndrome
- Liver disease
- Sedentary lifestyle or unhealthy diet
- Current or former smoker
How do I interpret the results?
Your results will show your TMAO concentration in micromoles (uM). Elevated levels indicate increased cardiovascular disease risk, though results should always be interpreted alongside other risk factors and clinical findings.
- Below 6.2 uM – Normal range; lower cardiovascular risk; continue healthy lifestyle and routine monitoring
- 6.2–10.0 uM – Moderately elevated; increased risk; implement dietary modifications and retest in 3–6 months
- Above 10.0 uM – Significantly elevated; higher cardiovascular risk; undergo comprehensive evaluation and adopt aggressive lifestyle changes
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
Proper preparation ensures accurate results:
- Fast for 10-12 hours before your blood draw—water is permitted
- Avoid all fish and seafood for 24 hours prior, as these foods significantly elevate TMAO levels
- Continue your regular medications unless instructed otherwise by your healthcare provider
- Inform the lab of any recent dietary changes or supplements you're taking
- Follow all instructions provided when you order to ensure the most reliable test results.
How often should I get tested?
Testing frequency depends on your cardiovascular risk profile and whether you're monitoring lifestyle interventions.
- Initial baseline screening – Once, then as directed by provider
- Elevated TMAO with lifestyle changes – Every 3–6 months to monitor progress
- Known cardiovascular disease – Every 6–12 months or as recommended
- High-risk factors (diabetes, obesity) – Annually or biannually
- Normal results, low risk – Every 2–3 years or with routine physical
Discuss your individual testing schedule with your healthcare provider based on your complete cardiovascular risk profile and health goals.
Why early detection matters
Cardiovascular disease remains the leading cause of death worldwide, responsible for over 17.9 million deaths annually (WHO 2023). Early identification through TMAO testing combined with lifestyle modification can potentially reduce cardiovascular event rates by 20-30% in at-risk groups (AHA 2023). Unlike sudden cardiac events, elevated TMAO can be detected years before symptoms appear, giving you time to take preventive action. Studies show that dietary changes reducing red meat intake, along with probiotics and increased physical activity, can successfully lower TMAO levels. With fasting TMAO blood tests showing diagnostic accuracy above 80% when combined with other markers, this test empowers you to take control of your cardiovascular health before disease develops.
Related tests you may consider
Lipid Panel – Comprehensive cholesterol profile including LDL, HDL, and triglycerides for complete heart risk assessment
High-sensitivity C-Reactive Protein (hs-CRP) – Measures inflammation levels, a complementary cardiovascular risk marker
HbA1c – Assesses long-term blood sugar control for diabetes-related heart disease risk
