Lipemia interference documentation is a regulatory requirement for every IVD assay — yet the methodology is poorly standardised across the industry. Many manufacturers run interference studies once, insufficiently, and then face reviewer questions during IVDR submissions. This article walks through the correct approach step by step.
Why Lipemia Interference Documentation Is Not Optional Under IVDR
EU IVDR 2017/746 requires manufacturers to characterise the performance of their IVD under conditions representative of intended use — including conditions where interferents may be present. Lipemia is explicitly addressed because it is the most common and most variable preanalytical matrix condition in clinical samples.
The reference standard for lipemia interference testing is CLSI EP7 (Interference Testing in Clinical Chemistry, 3rd edition). For automated HIL index detection systems, the companion document is CLSI C56. Both are accepted by European notified bodies as the appropriate methodology for interference characterisation.
Designing the Study: The Four Key Decisions
1. Choose your baseline matrix
Your baseline (zero-lipid) matrix must be human serum or plasma that is optically clear and contains your analyte of interest at a clinically relevant concentration. Delipidated human serum (SP1010) is the standard choice — it removes lipoproteins while leaving IgG, albumin and most proteins intact, providing a realistic matrix baseline.
Do not use buffer or BSA solutions as your baseline. They produce a matrix effect — the assay behaves differently in buffer vs. serum — which contaminates your interference data with a matrix effect signal that is not lipemia-related.
2. Choose your lipid spike material
CLSI EP7 accepts two approaches for creating controlled lipemia levels:
- Intravenous lipid emulsion (Intralipid): Intralipid 20% is the most widely used spiking material. It creates reproducible turbidity. Limitation: Intralipid particles differ in size distribution from native chylomicrons, so some assays show different interference patterns with Intralipid vs. native lipemia.
- Native lipemic material: Ultracentrifugation-enriched lipid fraction from patient lipemic sera. More representative of clinical interference, but requires substantial donor sample volumes. Preferred when Intralipid-native discordance is suspected.
SeamlessBio SP1010 Human Serum Delipidated — optically clear, EU-qualified donors, full COA, lot reservation. Ready to use as your zero-lipid matrix for CLSI EP7 interference studies.
3. Define your acceptance criterion
Before running the study, define the maximum allowable bias caused by lipemia. This is your acceptance criterion and it must be defined prospectively — before you see the data. Common approaches:
- Clinical decision limit: maximum bias that would not change a clinical decision (e.g. ±10% for most quantitative assays)
- Total allowable error (TEa): the CLIA or Ricos biological variation-based TEa for your analyte
- Assay-specific threshold: defined in your device specifications based on intended use
4. Choose your concentration range
Test at a minimum of 5–7 triglyceride concentrations from baseline to the maximum expected in clinical samples. A practical range for most clinical chemistry assays: 0 (baseline/delipidated), 200, 500, 1000, 2000, 3000 and 5000 mg/dL triglycerides. Severely lipaemic samples in clinical practice can exceed 10,000 mg/dL in patients with familial hypertriglyceridaemia.
Calculating and Reporting Bias
| Triglycerides (mg/dL) | Assay Reading | Baseline Reading | Absolute Bias | % Bias | Pass/Fail (±10%) |
|---|---|---|---|---|---|
| 0 (baseline) | 5.2 mmol/L | 5.2 mmol/L | 0 | 0% | Pass |
| 500 | 5.3 mmol/L | 5.2 mmol/L | +0.1 | +1.9% | Pass |
| 1000 | 5.5 mmol/L | 5.2 mmol/L | +0.3 | +5.8% | Pass |
| 2000 | 5.9 mmol/L | 5.2 mmol/L | +0.7 | +13.5% | Fail |
In this example the assay passes at triglyceride concentrations up to 1000 mg/dL but fails at 2000 mg/dL. The interference threshold would be reported as "triglycerides ≤1000 mg/dL" in the instructions for use and technical file.
What Your IVDR Technical File Must Include
- Study design description: baseline matrix (delipidated serum, lot number), spiking material (Intralipid or native), concentration range, number of replicates, instrument and reagent lot
- Raw data table with all measurements
- Calculated % bias at each concentration level
- Acceptance criterion (pre-defined) and pass/fail determination
- Interference threshold (maximum concentration at which assay passes)
- Statement of matrix material appropriateness (EU donor origin, processing method)
Zero-lipid baseline matrix for CLSI EP7 lipemia interference studies. EU donors, optically clear, full COA.
View product → shop.seamlessbio.de Human Serum Universal NegativeAlternative baseline matrix — screened negative, full serum composition. For assays requiring intact complement or hormone profile.
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