NHA Certified Phlebotomy Technician (CPT)Specimen HandlingEasy
A phlebotomy technician is preparing to process a potassium specimen collected in a lavender-top tube. Which of the following is the most critical step to ensure accurate results?
- APlacing the tube on ice immediately after collection.
- BStoring the specimen at room temperature for an hour.
- CInverting the tube gently 8-10 times.
- DCentrifuging the specimen immediately after collection.
Show answer & explanationAnswer & explanation
Correct answer: C. Inverting the tube gently 8-10 times.
Lavender-top tubes contain EDTA, an anticoagulant that must be thoroughly mixed with the blood to prevent clotting and ensure accurate hematology results. Gentle inversion is crucial for this mixing.
Why the other options are wrong
- A. Placing on ice is generally for tests like ammonia or lactic acid, not routine potassium in an EDTA tube.
- B. Storing at room temperature for an hour without proper mixing can lead to clotting and inaccurate results for EDTA tubes.
- D. Immediate centrifugation is not appropriate for a lavender-top tube, as it requires proper mixing of the anticoagulant first.
EDTA Tube Mixing
EDTA tubes contain an anticoagulant that must be thoroughly mixed with the blood sample to prevent clotting and ensure accurate test results, particularly for hematology.
- Invert gently 8-10 times.
- Prevents microclots.
- Essential for CBC and other hematology tests.
Memory trick: Mix the magic potion, don't let it clot, for accurate count, that's what you've got!