Laboratory Operations, quick reference 8 of 10
08 / 10 · Laboratory Operations
Hemolysis, lipemia, and icterus
Appearance and interference in serum or plasma
Hemolysis, lipemia, and icterus can alter serum or plasma measurements. The same specimen may be acceptable for one test and unsuitable for another because each method responds differently to interference.1
Clear, pale yellow
Pink to red
Cloudy to milky
Deep yellow to brown
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| Finding | How results may change | Practical implication |
|---|---|---|
| Hemolysis | Cell rupture releases potassium and lactate dehydrogenase. Free hemoglobin absorbs light and can affect chemical reactions. | Potassium released from the red cells raises the potassium result. The size and direction of other biases vary by analyte and method. A recollected specimen may be free of hemolysis caused by collection. In vivo hemolysis may persist after recollection.2 |
| Lipemia | Particles scatter light and affect sampling. Reduced plasma-water fraction affects methods that dilute the sample. | Indirect ion-selective electrodes can report falsely low sodium. Direct electrodes generally avoid this water-fraction effect. Lipid removal may also remove analyte.3 |
| Icterus | Bilirubin absorbs light and can react with assay components, including oxidants. | Effects differ between assays. A fresh draw may still be icteric, so an alternate validated method may be needed.1 |
What the interference index means
Mixed interferences can obscure the appearance. A visual estimate cannot determine whether a specimen is acceptable.2
An instrument interference index estimates hemoglobin, bilirubin, or turbidity from optical readings. Its scale comes from the instrument method and cannot be inferred from color alone. A lipemia index measures turbidity and gives no triglyceride concentration. Each platform has its own index scale and limits.1,3
Review each affected test
Compare the index with the manufacturer's interference data and the laboratory's verified limit for that test. Suppress, qualify, recollect, or use a validated alternate method as the procedure directs. A patient specimen can be affected even when controls pass.1,2