Certified Medical Assistant (CMA AAMA)Procedures, Examinations and DiagnosticsEasy
A medical assistant is instructed to collect and transport a blood specimen for bilirubin testing. Which special handling step is required to preserve the integrity of the sample?
- APlace the tube immediately into a warming block at 37°C
- BInvert the tube vigorously 20 times before transport
- CStore the specimen at room temperature for 24 hours before centrifuging
- DWrap the tube in aluminum foil or use an amber tube to protect it from light
Show answer & explanationAnswer & explanation
Correct answer: D. Wrap the tube in aluminum foil or use an amber tube to protect it from light
Bilirubin is a light-sensitive analyte that degrades when exposed to light, causing falsely decreased results. Protecting the specimen with foil or an amber tube prevents photodegradation during transport and storage.
Why the other options are wrong
- A. Warming is unnecessary and could accelerate analyte breakdown.
- B. Excessive inversion can cause hemolysis, not relevant to light protection.
- C. Prolonged room-temperature storage risks further degradation, not protection.
Light-Sensitive Specimens
Certain analytes like bilirubin and vitamin B12 degrade when exposed to light, requiring specimens to be shielded during collection and transport.
- Bilirubin degrades with light exposure
- Use amber tubes or foil wrapping
- Applies also to vitamin B12, folate, beta-carotene
Memory trick: Bilirubin hides from the sun—wrap it in foil!