A specimen has ALP ordered. Which factors could cause false results?

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Multiple Choice

A specimen has ALP ordered. Which factors could cause false results?

ALP measurement relies on a colorimetric reaction in serum, so anything that changes the sample’s optical properties or the enzyme’s activity can distort the result. Hemolysis releases red blood cell contents, including hemoglobin, into the serum. Hemoglobin absorbs light and can interfere with the color readout of the ALP assay, causing an apparent change in activity—often a false reading. In addition, substances released from disrupted cells can alter the reaction environment and enzyme performance, making the result unreliable. Delaying analysis also shifts the reading away from the true in‑vivo level. If the sample isn’t processed promptly, enzyme activity can change during storage—proteolysis, temperature effects, or other biochemical changes may degrade or alter ALP, yielding a falsely high or low value when finally measured. Prompt processing and appropriate storage help preserve the enzyme’s true activity and avoid these artifacts. Lipemia can also interfere with some assays due to turbidity or spectral issues, but the combination of hemolysis and delayed processing is the more consistent source of false ALP results in many preanalytic contexts, which is why both factors are listed as potential causes.

ALP measurement relies on a colorimetric reaction in serum, so anything that changes the sample’s optical properties or the enzyme’s activity can distort the result. Hemolysis releases red blood cell contents, including hemoglobin, into the serum. Hemoglobin absorbs light and can interfere with the color readout of the ALP assay, causing an apparent change in activity—often a false reading. In addition, substances released from disrupted cells can alter the reaction environment and enzyme performance, making the result unreliable.

Delaying analysis also shifts the reading away from the true in‑vivo level. If the sample isn’t processed promptly, enzyme activity can change during storage—proteolysis, temperature effects, or other biochemical changes may degrade or alter ALP, yielding a falsely high or low value when finally measured. Prompt processing and appropriate storage help preserve the enzyme’s true activity and avoid these artifacts.

Lipemia can also interfere with some assays due to turbidity or spectral issues, but the combination of hemolysis and delayed processing is the more consistent source of false ALP results in many preanalytic contexts, which is why both factors are listed as potential causes.

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