When receiving a laboratory test report, technical phrases like “trace-lysed” can be confusing. This term is used by labs to describe the quality of the sample analyzed. A “trace-lysed” result indicates a slight issue was detected with the specimen before or during testing. Understanding this notation requires knowing its two components: the minimal quantity indicated by “trace” and the biological event described by “lysed.” This article explains this finding, clarifying what it means for the accuracy of your results and what steps may follow.
What the Two Parts of the Term Mean
The term “lysed” refers to the process of lysis, which is the rupturing or breaking down of a cell membrane. In the context of a blood sample, this specific event is known as hemolysis, where red blood cells (erythrocytes) burst. Red blood cells are essentially small, fragile packages designed to carry oxygen, and when their membranes are compromised, they spill their contents into the surrounding fluid, which is the plasma or serum being tested. The released contents, primarily the protein hemoglobin, are what the laboratory detects to identify the lysis.
The released hemoglobin gives the fluid a pink or reddish tint, interfering with optical instruments. Red blood cells contain high concentrations of substances like potassium and lactate dehydrogenase (LDH). When cells lyse, these substances flood the sample, potentially causing falsely elevated measurements for those specific tests.
The first part, “trace,” is a quantitative measure describing the severity of cell rupture. It signifies that the amount of lysis is minimal, often just meeting the lowest detection threshold. This contrasts with terms like “moderate” or “grossly hemolyzed,” which indicate significant cellular breakdown. A “trace” finding suggests only a small fraction of red blood cells were affected.
This minimal breakdown means the interference caused by released cell contents is slight, but the lab flags it as a technical observation. It warns the clinician about a minor compromise to the sample’s integrity, suggesting some results may be slightly inaccurate.
Why Cells Lyse in a Sample
The most frequent reason a blood sample is labeled “trace-lysed” is due to external factors during collection or handling, known as in vitro (in glass) hemolysis or pre-analytical error. A common cause is improper blood drawing technique, such as using a narrow gauge needle. This forces red blood cells through a constricted opening under high pressure, causing mechanical stress that damages cell membranes and leads to rupture.
Other handling issues include shaking the collection tube too vigorously during mixing or forcing the blood into the tube from a syringe. Exposure to extreme temperatures, such as freezing or excessive heat during transport or storage, can also compromise the integrity of the cell membranes. Even minor delays in processing the sample, particularly separating the serum or plasma from the cells, can contribute to a trace level of lysis over time.
While less common, hemolysis can sometimes be attributed to biological factors within the patient’s body, known as in vivo (in the living) hemolysis. Certain health conditions, such as hemolytic anemias, infections, or inherited disorders, can make red blood cells unusually fragile and prone to breaking down.
However, for a result noted only as “trace-lysed,” the cause is statistically much more likely to be related to the collection and handling procedure rather than an internal medical condition. The majority of trace hemolysis cases are the result of minor technical issues during the phlebotomy process. If the lysis were due to a significant internal medical issue, the level of hemolysis would typically be much higher than a mere “trace” amount.
The Clinical Significance of a Trace Result
A “trace-lysed” notation alerts the clinician that the sample quality is slightly compromised. The most sensitive analytes are potassium, lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and phosphorus, which are highly concentrated inside red blood cells. A trace finding can cause a small, but measurable, increase in the reported values for these substances.
Because even a slight elevation in substances like potassium can have serious clinical implications, the laboratory may flag the result or add a comment warning of potential interference. For a trace amount, the result is often reported with a caveat, depending on the lab’s policy. This warning is crucial when the measured value is near a clinical decision point, as a slight, false elevation could change a diagnosis.
The next step for the clinician depends on the context of the results. If the patient is otherwise healthy and the potentially affected values are within the normal range, the doctor may choose to disregard the trace finding, assuming the error is minor. Conversely, if the potentially inaccurate value is significantly high or low, or if the patient has symptoms suggesting an underlying issue, the physician will likely request a redraw of the blood sample.
Ordering a redraw is the most common action following a trace-lysed result, as it eliminates uncertainty. This confirms whether the initial result reflected the patient’s physiology or was an artifact of the collection process. If the second sample is also hemolyzed, or if other clinical indicators suggest it, the physician may then consider targeted testing for an underlying biological cause.