What laboratory test can I order to evaluate omega‑3 status in a patient being assessed for hypertriglyceridemia, cardiovascular risk, pregnancy, or neurocognitive concerns?

Laboratory Testing for Omega-3 Status

Order the Omega-3 Index, which measures EPA+DHA as a percentage of total fatty acids in red blood cell membranes, using standardized gas chromatography-mass spectrometry (GC-MS) analysis. 1, 2

What the Omega-3 Index Measures

The Omega-3 Index quantifies the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) expressed as a percentage of total fatty acids in erythrocyte membranes 1, 3. This biomarker reflects medium- to long-term omega-3 intake (approximately 120 days, the lifespan of red blood cells) and provides a more stable assessment than plasma measurements 1, 2.

The test detects approximately 25 fatty acids in red blood cells, including both cis and trans isomers, with EPA concentrations ranging from 3.53 to 105.89 µg/mL (11.7–350 µmol/L) and DHA from 12.19 to 214.42 µg/mL (37.1–652.7 µmol/L) in healthy individuals 1.

Target Ranges and Clinical Interpretation

Cardiovascular Risk Stratification

• Target range: 8–11% for optimal cardiovascular protection 2, 4
• Levels below 4% indicate high cardiovascular risk 2
• No human has an Omega-3 Index <2%, representing a vital minimum 2

Clinical Correlations

• Total mortality, cardiovascular mortality, myocardial infarction, stroke, and blood pressure all correlate inversely with the Omega-3 Index 2
• An Omega-3 Index ≥4% is associated with improved cognitive testing scores and delayed cognitive aging 5
• The 8–11% target range is supported for pregnancy outcomes 2

Technical Specifications for Ordering

Request standardized HS-Omega-3 Index® analysis using gas chromatography with electron impact mass spectrometry (GC-EI-MS), as this is the scientifically validated method 1, 2. Non-standardized methods produce results that cannot be reliably compared to the established 8–11% target range 2.

Analytical Performance

• Intra-assay and day-to-day variations are <5% 1
• Linearity extends to EPA concentrations of 250 µg/mL (830 µmol/L) 1
• Limit of detection for EPA is 0.36 µg/mL (1.2 µmol/L) 1
• No difference between fasting and postprandial samples, so fasting is not required 1

Clinical Applications by Indication

Hypertriglyceridemia

Use the Omega-3 Index to guide dosing of EPA+DHA supplementation, as clinical events correlate with achieved levels rather than prescribed dose due to inter-individual bioavailability variation 2, 6. For severe hypertriglyceridemia, free fatty acid (FFA) formulations exhibit significantly higher bioavailability than ethyl ester forms because they do not require pancreatic enzyme hydrolysis for absorption 6.

Cardiovascular Risk Assessment

The Omega-3 Index functions as an independent risk factor for fatal coronary heart disease and has been validated across 456 published studies over 20 years 4. Recent data confirm its utility in predicting cardiovascular mortality, with the metric now used to study a remarkably large number of health conditions beyond cardiovascular disease 4.

Neurocognitive Assessment

Higher Omega-3 Index values correlate directly with complex brain functions, with DHA comprising 25% of total fatty acids in the cerebral cortex 5. The test helps identify patients who may benefit from targeted supplementation for cognitive protection 5.

Pregnancy Monitoring

The 8–11% target range is specifically supported for pregnancy, as omega-3 status impacts maternal and fetal outcomes 2.

Common Pitfalls to Avoid

• Do not use non-standardized laboratory methods, as even small analytical differences produce large result variations that cannot be compared to the validated 8–11% target range 2
• Do not rely on dietary intake estimates alone, as bioavailability of EPA and DHA varies substantially between individuals 2
• Do not interpret results without considering the analytical method used, as results from non-HS-Omega-3 Index® methods raise ethical issues when compared to the established target range 2
• Do not assume the Omega-6:Omega-3 ratio is equivalent, as this older metric has theoretical and practical difficulties and should be replaced by the Omega-3 Index, which focuses on the primary Western diet deficiency (EPA and DHA) 3

Monitoring and Follow-Up

Recheck the Omega-3 Index 3–4 months after initiating or adjusting supplementation, as this timeframe allows for red blood cell turnover and reflects the new steady-state omega-3 status 1, 2. Individualize EPA+DHA doses based on achieved levels rather than fixed dosing, as the goal is reaching the 8–11% target range using toxin-free sources 2.