Application of serum pools in insulin harmonization: Commutability and stability.
Author(s): Deng Y, Zhang C, Wang J, Zeng J, Zhang J, Zhang T, Zhao H, Li M, Zhao Y, Gan W, Shao Y, Yu H, Zhou W, Zhang C.
Publication: Ann Clin Biochem, 2023, Vol. , Page 45632231159291
PubMed ID: 36750430 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to investigate the stability of insulin in serum specimens stored at -80°C, -20°C, 4°C, and room temperature and to compare insulin levels quantified using six different clinical chemistry autoanalyzers.
Conclusion of Paper
Insulin levels were stable in serum pools stored for 16 days at 4°C and one year at either -80°C or -20°C, but declined when serum pools were stored at room temperature for ≥12 h. While insulin levels in serum specimens were strongly correlated between any pair of assays investigated (R=0.911-0.980) and median relative differences were ≤15%, in specimens with low insulin levels the relative difference between methods sometimes exceeded the allowable error of ±32%. After the machines were recalibrated, median relative differences were ≤6%, but the intercept of Passing and Bablok regression lines increased for all assay pairs indicating that poor agreement occurred between assays when specimen insulin levels were low. For the lyophilized serum pools, the results were only comparable between three of the six assays evaluated.
Studies
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Study Purpose
The purpose of this study was to investigate the stability of insulin in serum specimens stored at -80°C, -20°C, 4°C, and room temperature and to compare insulin levels quantified using six different clinical chemistry assays. This study used leftover serum specimens from 69 patients (diagnosis unspecified) that had been stored at 4°C for <24 h and then stored at -80°C. Ten pooled specimens were created by thawing serum with similar insulin levels, pooling, storing specimens overnight at 4°C on a magnetic stirring plate, filtering through a 0.45 µm or0.22 µm filter, aliquoting, storing frozen aliquots at -80°C, and shipping samples on dry ice. Additionally, three external quality assessment, lyophilized serum pools were obtained from the Chinese National Center of Clinical Laboratories. Stability was investigated by storing aliquots of the three serum pools at 4°C, and room temperature for 2 h, 4 h, 12 h, 24 h, 2 days, 4 days, 7 days and 16 days.at -80°C, and -20°C for 1, 6, 9 and 12 months and in liquid nitrogen for the same durations (control). Agreement in insulin levels were explored by correlational analysis of results obtained using six different clinical chemistry autoanalyzers and assays: Roche Cobas e801, Abbott I2000, Siemens ADVIA Centaur XP, Beckman Dxi800, Mindray CL8000, and Snibe Maglumi X8.
Summary of Findings:
Insulin levels were stable in serum pools stored for 16 days at 4°C and one year at -80°C or -20°C but declined when serum pools were stored at room temperature for ≥12 h. Serum specimens with insulin levels at the low end of the clinical range (<120 pmol/L) showed inconsistency in quantified insulin levels between the assays evaluated. Above this threshold comparable results were among all six assays was observed for two of the three serum pools, with some inconclusive results found for the other three pools. In contrast, results from lyophilized serum pools were only comparable between three of the six assays. Insulin levels in the 69 serum specimens were strongly correlated between any pair of the assays investigated (R=0.911-0.980) and median relative differences were ≤15%. Nevertheless, in some specimens with low insulin levels the relative difference that occurred between methods exceeded the allowable error of ±32%. After the machines were recalibrated the median relative differences were ≤6%, but the intercept of Passing and Bablok regression lines increased for all assay pairs, indicating poor agreement between assays when specimen insulin levels were low.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Peptide Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage temperature -80°C
-20°C
4°C
Room temperature
Clinical chemistry/auto analyzer Specific Technology platform Roche Cobas e801
Abbott I2000
Siemens ADVIA Centaur XP
Beckman Dxi800
Mindray CL8000
Snibe Maglumi X8
Storage Storage duration 2 h
4 h
12 h
24 h
2 days
4 days
7 days
16 days
1 month
6 months
9 months
12 months