Serial bilirubin determinations showing fluctuations are best explained by which factor?

Serial bilirubin determinations showing fluctuations are best explained by which factor?

• A. Sample hemolysis and hemoglobin deterioration
• B. Sample exposure to light
• C. Sample left in a warm location
• D. Reagent deterioration

Answer: (B)

Bilirubin is highly photosensitive, so light exposure alters its measured concentration. When bilirubin-containing samples are exposed to light, photodegradation and isomerization occur, producing forms that absorb differently at the assay wavelength. This can cause the measured bilirubin to rise or fall between serial determinations if samples are not consistently protected from light, leading to apparent fluctuations. Other factors like hemolysis, warming, or reagent issues can affect results, but they don’t typically produce the same pattern of inconsistent measurements driven mainly by light exposure. To prevent this, protect bilirubin samples from light (amber tubes, foil wrap) and minimize time in light during handling.

Bilirubin is highly photosensitive, so light exposure alters its measured concentration. When bilirubin-containing samples are exposed to light, photodegradation and isomerization occur, producing forms that absorb differently at the assay wavelength. This can cause the measured bilirubin to rise or fall between serial determinations if samples are not consistently protected from light, leading to apparent fluctuations. Other factors like hemolysis, warming, or reagent issues can affect results, but they don’t typically produce the same pattern of inconsistent measurements driven mainly by light exposure. To prevent this, protect bilirubin samples from light (amber tubes, foil wrap) and minimize time in light during handling.