The correct answer to the problem: C) Analyzer lamp defect
Explanation: Bilirubin is measured in a biochemical analyzer by a photometric method, most often in the ultraviolet or blue-green spectral range (usually around 450 nm for indirect and 600 nm for direct bilirubin). If the analyzer lamp (usually xenon or halogen) begins to lose intensity in a certain part of the spectrum, then the indicators dependent on this range will be distorted — most often underestimated.
In this problem:
- The deviations are stable and concern a single parameter (bilirubin),
- Other parameters are normal,
- Control materials, reagents, temperature conditions — excluded,
- Recalibration does not help, — all this points to a technical defect in the light source, namely the lamp responsible for the spectrum in which bilirubin is read.
The problem does not affect other parameters, as they are measured in different wavelength ranges. After replacing the lamp, the bilirubin value usually returns to normal. Therefore, timely technical maintenance and monitoring of lamp operating hours are extremely important in photometric analyzers.
