NHA Certified Phlebotomy Technician (CPT)Specimen HandlingMedium
A phlebotomy technician is preparing to process a specimen for a blood ammonia level. Which of the following steps is critical to maintain the specimen's integrity?
- ACentrifuge the specimen immediately and place on ice.
- BTransport the specimen at room temperature.
- CAllow the specimen to clot for 30 minutes at room temperature.
- DProtect the specimen from light.
Show answer & explanationAnswer & explanation
Correct answer: A. Centrifuge the specimen immediately and place on ice.
Blood ammonia levels increase rapidly at room temperature due to cellular metabolism. Therefore, the specimen must be placed on ice immediately after collection and centrifuged promptly to separate plasma from cells, then kept cold.
Why the other options are wrong
- B. Transporting at room temperature will lead to a significant increase in ammonia levels, causing inaccurate results.
- C. Allowing it to clot at room temperature will lead to false elevation of ammonia due to ongoing cellular metabolism.
- D. Ammonia is not typically light-sensitive, so light protection is not the primary concern.
Ammonia Specimen Handling
Ammonia specimens require immediate chilling and prompt plasma separation to inhibit cellular metabolism, which can rapidly increase ammonia levels in vitro, leading to falsely elevated results.
- Collected in EDTA or heparin (green top) tubes.
- Place on ice immediately after collection.
- Centrifuge and separate plasma within 15-30 minutes.
- Keep plasma cold/frozen until testing.
Memory trick: Ammonia's hot, so keep it cold, or the true value won't be told.