Two-year stability of NT-proBNP in frozen samples using the Roche Elecsys system

Area of Science:

• Biochemistry
• Clinical Chemistry
• Laboratory Medicine

Background:

• In vitro stability of NT-proBNP at room temperature and 4°C is well-established.
• Limited data exists on the long-term frozen storage stability of NT-proBNP.
• Understanding frozen storage stability is crucial for clinical evaluations and biobanking.

Purpose of the Study:

• To evaluate the stability of NT-proBNP after two years of frozen storage at -20°C.
• To determine the impact of long-term frozen storage on NT-proBNP assay results.
• To assess the reliability of NT-proBNP measurements from frozen samples for clinical use.

Main Methods:

• Collected 97 heparinized plasma samples.
• Stored samples at -20°C for two years.
• Measured NT-proBNP concentrations using the Roche Elecsys system before and after storage.

Main Results:

• A slight but statistically significant decrease in NT-proBNP concentration was observed after frozen storage.
• Over 90% of samples showed a decrease of less than 10%.
• High correlation (r=0.99) was found between fresh and stored sample values, with a predictive equation provided.

Conclusions:

• NT-proBNP is stable for at least two years when stored at -20°C.
• Long-term frozen storage does not lead to substantial loss of NT-proBNP immunoreactivity.
• Stored samples can be reliably used for NT-proBNP measurements in clinical settings.