Investigating non-reproducible high-sensitivity cardiac troponin T results in real-world practice
Zeynep Şule Evren1, Kamil Taha Uçar1
1Department of Medical Biochemistry, Başakşehir Çam and Sakura City Hospital, Istanbul, Türkiye.
Insights
Non-reproducible high-sensitivity cardiac troponin T (hs-cTnT) results occur in 3.3% of tests, particularly in plasma and at lower concentrations. Most resolve upon repeat testing, impacting clinical decisions and workflow.
Area of Science:
- Clinical Chemistry
- Biomarker Analysis
- Diagnostic Accuracy
Background:
- High-sensitivity cardiac troponin T (hs-cTnT) is crucial for diagnosing myocardial injury.
- Non-reproducible hs-cTnT results can complicate clinical interpretation.
- Limited real-world data exists on the frequency and impact of these outlier results.
Purpose of the Study:
- To evaluate the frequency and characteristics of non-reproducible hs-cTnT results in a clinical laboratory setting.
- To assess the influence of sample matrix (serum vs. plasma) and concentration on result reproducibility.
- To determine the impact of repeat testing on turnaround time and clinical decision-making.
Main Methods:
- Retrospective analysis of 10,815 hs-cTnT repeat measurements from June 2023 to December 2025.
- Identification of non-reproducible results using a critical difference (CD)-based approach and the common change criteria (3C).
- Comparison of outlier rates between serum and plasma, and between different trigger types (URL vs. delta), with assessment of directional changes and turnaround time.
Main Results:
- Non-reproducible hs-cTnT results were observed in 3.3% of repeat measurements.
- Outlier rates were significantly higher in plasma (5.4%) compared to serum (0.7%) (p < 0.001).
- Most non-reproducible results occurred at initial concentrations of 10-20 ng/L and typically decreased upon repeat testing (95.8%).
- Repeat testing introduced a median delay of 42 minutes.
Conclusions:
- Non-reproducible hs-cTnT results are a notable issue, influenced by sample type and concentration.
- The majority of these results represent transient elevations, potentially leading to unnecessary workflow delays.
- Selective repeat testing with careful interpretation is recommended to maintain analytical reliability and minimize delays in time-sensitive clinical decisions.
Objectives:
High-sensitivity cardiac troponin T (hs-cTnT) testing is central to myocardial injury diagnosis, but non-reproducible ("outlier") results may complicate interpretation. Real-world data on their frequency and implications remain limited. We evaluated non-reproducible hs-cTnT results in our laboratory.
Methods:
This retrospective study at Başakşehir Çam and Sakura City Hospital used hs-cTnT measurements from June 2023-December 2025. Non-reproducible results were identified by a critical difference (CD)-based approach applied to repeat testing of original serum and lithium-heparin plasma specimens on a Roche cobas e801 platform (fifth-generation assay). The common change criteria (3C) served as an alternative classifier. Chi-square tests compared outlier rates between serum and plasma and between URL-triggered and delta-triggered subgroups. Directional changes on repeat and additional turnaround time were also assessed.
Results:
Among 10,815 repeated measurements, non-reproducible results occurred in 3.3% (n = 356; 95% CI 2.97-3.64). They were more frequent in plasma than in serum (5.4% vs. 0.7%, p < 0.001) and most common at initial concentrations of 10-20 ng/L (n = 223), followed by 20-30 ng/L (n = 92). Rates were 2.29% in URL-triggered and 3.87% in delta-triggered repeats (p < 0.001). On repeat, most results decreased (95.8%); increases were uncommon (4.2%). Repeat testing added a median delay of 42 min. The 3C criterion identified 425 results, comprising all CD-flagged cases plus 69 additional.
Conclusions:
Non-reproducible hs-cTnT results occur with appreciable frequency and may be influenced by sample matrix and concentration range. Most represent isolated elevations decreasing on repeat, potentially affecting workflow and time-sensitive decisions. Selective repeat testing with careful interpretation may preserve analytical reliability while minimizing delays.
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