NHA Certified Phlebotomy Technician (CPT)Specimen HandlingHard
A phlebotomy technician is asked to retrieve a stored plasma specimen for a specialized hormone assay. The specimen was collected 3 months ago. Which of the following storage conditions is most likely to have preserved the specimen's integrity for this duration?
- AStored in a light-protected container at room temperature.
- BFrozen at -20°C or colder.
- CRefrigerated at 2-8°C.
- DStored at room temperature (20-25°C).
Show answer & explanationAnswer & explanation
Correct answer: B. Frozen at -20°C or colder.
For long-term storage (e.g., several months) of plasma specimens for specialized assays like hormone testing, freezing at -20°C or colder is typically required. This low temperature effectively halts most enzymatic and chemical degradation processes, preserving analyte stability over extended periods.
Why the other options are wrong
- A. Light protection is important for some analytes, but it doesn't address the primary issue of long-term stability over 3 months at room temperature.
- C. Refrigeration is suitable for short-term storage (days to a couple of weeks), but not typically for 3 months for sensitive analytes.
- D. Room temperature for 3 months would lead to significant degradation of most analytes, especially hormones.
Long-Term Specimen Storage
For long-term preservation of sensitive analytes (e.g., hormones) in plasma or serum, specimens must be stored frozen at -20°C or colder to prevent degradation and maintain integrity for extended periods.
- Required for months/years of storage.
- Halts metabolic and chemical degradation.
- Thaw properly to avoid damage.
Memory trick: Long Term: Freeze it Deep, Secrets to Keep.