Evidence for stability of cardiac troponin T concentrations measured with a high sensitivity TnT test in serum and lithium heparin plasma after six-year storage at -80 °C and multiple freeze-thaw cycles.
Author(s): Henricks LM, Romijn FPHTM, Cobbaert CM
Publication: Clin Chem Lab Med, 2024, Vol. , Page
PubMed ID: 39479776 PubMed Review Paper? No
Purpose of Paper
This paper compared cardiac troponin T (cTnT) levels before and after case-matched serum and plasma from patients with suspected myocardial damage were stored for 3 and 6 years at -80°C. Serum and plasma specimens were collected as part of two different studies; each specimen cohort either experienced a delay to separation or in freezing (separated plasma/serum) although delays were not experimentally investigated.
Conclusion of Paper
cTnT levels were very strongly correlated between case-matched plasma and serum specimens (Spearman r=0.99580). When data from both studies were considered together, cTnT levels were significantly higher after 3 or 6 years of frozen storage in both serum (10.3 and 10.5 ng/L, respectively, versus 9.2 ng/L; p<0.001, both) and plasma (17.2 and 16.9 ng/L, respectively, versus 15.0 ng/L; p<0.001, both). However, when each study cohort was analyzed separately, a significant increase in cTnT levels was limited to the specimen cohort that experienced a delay in freezing of separated plasma/serum. When a threshold of >5 ng/L was applied for ruling in non-ST-segment elevation myocardial infarction (NSTEMI), 0% of serum and 6.6% of plasma specimens changed status after 3 years of storage and 0.8% of serum and 6.6% of plasma specimens changed status after 6 years of storage. When a threshold of <3 ng/L was applied for ruling out NSTEMI, 0% of serum and 19.2% of plasma specimens changed status after 3 years of storage and 0.5% of serum and 15.9% of plasma specimens changed status after 6 years of storage. The authors conclude that long-term storage at -80°C was more likely to adversely affect the clinical performance of lithium heparin plasma than serum.
Studies
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Study Purpose
This study compared levels of cardiac troponin T (cTnT) before and after case-matched serum and plasma from patients with suspected myocardial damage were stored for 3 and 6 years at −80°C. Blood was collected from ninety patients with suspected minor myocardial damage as part of two studies. Whole blood was collected into matched Venosafe serum and Lithium Heparin with gel separator Venosafe tubes, inverted, and stored at room temperature for <45 min (study with 60 patients) or 0, 3 and 6 h (delayed centrifugation study with 30 patients) before serum/plasma separation by centrifugation at 2500 g for 5 min at 4 °C. Plasma and serum was either immediately stored in cryovials at -80°C (delayed centrifugation study with 30 patients) or stored at room temperature or 2–8 °C for 0, 1, 2, 5, 12 and 24 h; for 24 h, 1 week, 4 weeks and 3 months at −20 °C; or 3 months at -80 °C (plasma/serum study with 60 patients) before transfer to -80°C. Specimens from both studies were thawed and analyzed together after 0, 3 and 6 years (1, 2 and 3 freeze-thaw cycles respectively). cTnT levels were quantified using the Roche Cobas e601 Modular E170 instrument. Clinically relevant changes were based on the European Society of Cardiology (ESC) guideline and defined as greater than the delta threshold for rule-in (>5 ng/L) and rule-out (<3 ng/L) of non-ST-segment elevation myocardial infarction (NSTEMI).
Summary of Findings:
cTnT levels were very strongly correlated between case-matched plasma and serum specimens (Spearman r=0.99580). When data from both studies were considered together, cTnT levels were significantly higher after 3 or 6 years of frozen storage in both serum (10.3 and 10.5 ng/L, respectively, versus 9.2 ng/L; p<0.001, both) and plasma (17.2 and 16.9 ng/L, respectively, versus 15.0 ng/L; p<0.001, both). However, when each study cohort was analyzed separately, a significant increase in cTnT levels was limited to the specimen cohort that experienced a delay in freezing of separated plasma/serum. When a threshold of >5 ng/L was applied for ruling in non-ST-segment elevation myocardial infarction (NSTEMI), 0% of serum and 6.6% of plasma specimens changed status after 3 years of storage and 0.8% of serum and 6.6% of plasma specimens changed status after 6 years of storage. When a threshold of <3 ng/L was applied for ruling out NSTEMI, 0% of serum and 19.2% of plasma specimens changed status after 3 years of storage and 0.5% of serum and 15.9% of plasma specimens changed status after 6 years of storage. The authors conclude that long-term storage at -80°C was more likely to adversely affect the clinical performance of lithium heparin plasma than serum.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Other diagnoses
- Cardiovascular Disease
Platform:
Analyte Technology Platform Protein Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage duration 0 years
3 years
6 years
Biospecimen Aliquots and Components Blood and blood products Plasma
Serum