- Instability of Plasma and Serum Progastrin-Releasing Peptide During Repeated Freezing and Thawing
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Jae-Eun Lee, Jin-Hyun Lee, Maria Hong, Seul-Ki Park, Ji-In Yu, So-Youn Shin, Shine Young Kim
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Osong Public Health Res Perspect. 2016;7(6):351-355. Published online December 31, 2016
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DOI: https://doi.org/10.1016/j.phrp.2016.11.004
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 Abstract
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- Objectives
Progastrin-releasing peptide (proGRP) is a promising biomarker for small cell lung cancer. However, not much is known about how sample processing and storage conditions affect the stability of proGRP. Here, we examined the effects of repeated freeze–thaw cycles on the stability of proGRP in plasma and serum.
Methods
Concentrations of proGRP were measured in plasma and serum samples exposed to two, three, or four freeze–thaw cycles and these were compared with values of corresponding samples exposed to one cycle (baseline). We also performed the area under the receiver-operating-characteristic curve (AUC) analysis to determine whether the differences of proGRP concentrations between each paired plasma and serum sample (ΔproGRP) can be used for identifying the samples that have been exposed to multiple freeze–thaw cycles.
Results
Concentrations of proGRP gradually decreased in both plasma and serum samples with increasing numbers of freeze–thaw cycles. Reduction rates of proGRP concentrations were greater in serum than in plasma samples and serum proGRP levels declined with statistical significance (p < 0.001) up to 10.1% after four freeze–thaw cycles. The ΔproGRP measurement showed fair accuracy (AUC = 0.741) for identifying samples that had been through four freeze–thaw cycles. The sensitivity was 82.8% and specificity was 62.1% at an optimal cut-off point of > 4.9.
Conclusion
Our study shows that the stability of circulating proGRP is affected in both plasma and serum samples by repeated freezing and thawing. We also show that ΔproGRP could be used for identifying paired plasma and serum samples subjected to multiple freeze–thaw cycles.
- Inorganic Phosphorus and Potassium Are Putative Indicators of Delayed Separation of Whole Blood
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Jae-Eun Lee, Maria Hong, Seul-Ki Park, Ji-In Yu, Jin-Sook Wang, Haewon Shin, Jong-Wan Kim, Bok-Ghee Han, So-Youn Shin
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Osong Public Health Res Perspect. 2016;7(2):90-95. Published online April 30, 2016
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DOI: https://doi.org/10.1016/j.phrp.2015.11.003
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1,362
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Abstract
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- Objectives
The delayed separation of whole blood can influence the concentrations of circulating blood components, including metabolites and cytokines. The aim of this study was to determine whether clinical-biochemistry analytes can be used to assess the delayed separation of whole blood.
Methods
We investigated the plasma and serum concentrations of five clinical-biochemistry analytes and free hemoglobin when the centrifugation of whole blood stored at 4°C or room temperature was delayed for 4 hours, 6 hours, 24 hours, or 48 hours, and compared the values with those of matched samples that had been centrifuged within 2 hours after whole-blood collection.
Results
The inorganic phosphorus (IP) levels in the plasma and serum samples were elevated ≥ 1.5-fold when whole-blood centrifugation was delayed at room temperature for 48 hours. Furthermore, the IP levels in the plasma samples showed excellent assessment accuracy [area under the receiver-operating-characteristic curve (AUC) > 0.9] after a 48-hour delay in whole-blood separation, and high sensitivity (100%) and specificity (95%) at an optimal cutoff point. The IP levels in the serum samples also exhibited good assessment accuracy (AUC > 0.8), and high sensitivity (81%) and specificity (100%). The potassium (K+) levels were elevated 1.4-fold in the serum samples following a 48-hour delay in whole-blood separation. The K+ levels showed excellent assessment accuracy (AUC > 0.9) following a 48-hour delay in whole-blood separation, and high sensitivity (95%) and specificity (91%) at an optimal cutoff point.
Conclusion
Our study showed that the IP and K+ levels in the plasma or serum samples could be considered as putative indicators to determine whether whole-blood separation had been delayed for extended periods.
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