Progastrin-releasing peptide: stability in plasma/serum and upper reference limit

Area of Science:

• Biochemistry
• Oncology
• Clinical Diagnostics

Background:

• Progastrin-releasing peptide (proGRP) shows potential as a tumor marker for small cell lung cancer (SCLC).
• Understanding proGRP stability and reference levels is essential for its clinical application.

Purpose of the Study:

• To evaluate the stability of proGRP in serum and plasma under various storage conditions.
• To determine proGRP levels in healthy individuals for establishing reference ranges.
• To provide a framework for future clinical studies utilizing proGRP as a biomarker.

Main Methods:

• Serum and plasma samples from SCLC patients and healthy individuals were analyzed for proGRP.
• Samples were tested immediately after collection and after storage under different conditions (temperature, duration).
• Protease inhibitors were used in some serum samples to assess their impact on stability.

Main Results:

• ProGRP in serum and plasma remained stable for 4 weeks when stored at -30°C.
• Serum proGRP was stable for 3 days at 4°C but degraded at room temperature.
• EDTA plasma showed increased proGRP concentrations upon storage at room temperature and 4°C.
• No significant difference in proGRP levels was found between serum and EDTA plasma when assayed immediately.
• A 97.5-percentile reference limit was established at 58.9 ng/l, with levels correlated to age, sex, BMI, creatinine, and smoking status.

Conclusions:

• Serum is the preferred specimen for proGRP measurement.
• Optimal storage for serum proGRP is at 4°C, with analysis recommended within 3 days.
• These findings establish guidelines for reliable proGRP quantification in clinical settings.