Which analytes are commonly affected by light exposure?

• A. Bilirubin and some carotenoids
• B. Glucose and insulin
• C. Potassium and bicarbonate
• D. Hemoglobin and iron

Answer: (A)

Light exposure can cause photochemical changes in some blood analytes, altering what the lab measures. Bilirubin is a well-known photosensitive pigment; when a specimen is exposed to light, bilirubin can break down into lumirubin and other products, changing the colorimetric signal and often yielding falsely low results if the sample isn’t protected. Some carotenoids, like beta-carotene, are also sensitive to light and can degrade, affecting their measured levels. In contrast, substances such as glucose, insulin, potassium, bicarbonate, hemoglobin, and iron are not primarily affected by light exposure in routine handling, so they don’t typically show changes due to light. That’s why the correct answer is bilirubin and some carotenoids.