Serum cardiac troponin I in canine syncope and seizures

Abstract Background: Up to a 20-fold variation in serum cardiac troponin I (cTnI) concentration may be observed for a given patient sample with different analytical methods. Because more limited variation is seen for control materials and for purified cTnI, we explored the possibility that cTnI was present in altered forms in serum. Methods: We used four recombinantly engineered cTnI fragments to study the regions of cTnI recognized by the Stratus®, Opus®, and ACCESS® immunoassays. The stability of these regions in serum was analyzed with Western blot. Results: The measurement of several control materials and different forms of purified cTnI using selected commercial assays demonstrated five- to ninefold variation. Both the Stratus and Opus assays recognized the N-terminal portion (NTP) of cTnI, whereas the ACCESS assay recognized the C-terminal portion (CTP) of cTnI. Incubation of recombinant cTnI in normal human serum produced a marked decrease in cTnI concentration as determined with the ACCESS, but not the Stratus, immunoassay. Western blot analysis of the same samples using cTnI NTP- and CTP-specific antibodies demonstrated preferential degradation of the CTP of cTnI. Conclusions: The availability of serum cTnI epitopes is markedly affected by the extent of ligand degradation. The N-terminal half of the cTnI molecule was found to be the most stable region in human serum. Differential degradation of cTnI is a key factor in assay-to-assay variation.

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An immunoprecipitation coupled with fluorescent Western blot analysis for the characterization of a model secondary serum cardiac troponin I reference material

Clinica Chimica Acta ◽

10.1016/j.cca.2010.09.017 ◽

2011 ◽

Vol 412 (1-2) ◽

pp. 107-111 ◽

Cited By ~ 7

Author(s):

Hua-Jun He ◽

Mark S. Lowenthal ◽

Kenneth D. Cole ◽

David Bunk ◽

Lili Wang

Keyword(s):

Reference Material ◽

Western Blot ◽

Blot Analysis ◽

Cardiac Troponin ◽

Western Blot Analysis ◽

Troponin I ◽

Cardiac Troponin I ◽

Serum Cardiac Troponin

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Improved detection of minor ischemic myocardial injury with measurement of serum cardiac troponin I

Clinical Chemistry ◽

10.1093/clinchem/43.11.2047 ◽

1997 ◽

Vol 43 (11) ◽

pp. 2047-2051 ◽

Cited By ~ 111

Author(s):

Fred S Apple ◽

Alireza Falahati ◽

Pamela R Paulsen ◽

Elizabeth A Miller ◽

Scott W Sharkey

Keyword(s):

Cardiac Troponin ◽

Myocardial Injury ◽

Troponin I ◽

Cardiac Troponin I ◽

Clinical Sensitivity ◽

Reference Limit ◽

Normal Limits ◽

Serial Serum ◽

Upper Reference Limit ◽

Serum Cardiac Troponin

Abstract This study compared the diagnostic accuracy of the measurement of serum cardiac troponin I (cTnI) with creatine kinase (CK) MB mass in patients with minor myocardial injury whose measured total CK activity did not exceed twice the upper reference limit (300 U/L for men; 200 U/L for women). Forty-eight consecutive patients presenting with chest pain and with in-hospital documentation of myocardial injury were enrolled. Electrocardiogram, echocardiogram, and serial serum CK-MB mass, cTnI, and total CK were measured over 36 h after admission. Peak total CK activity was within normal limits in 28 patients (58%). The mean (±SD) peak CK-MB mass and cTnI concentrations were: 16.4 (11.8) μg/L and 132 (13.0) μg/L; respectively. The peak biochemical marker index (defined as CK-MB or cTnI divided by its respective upper reference limit) was significantly (P <0.05) higher for cTnI than for CK-MB from 7 to 36 h. The clinical sensitivity for detection of myocardial injury for cTnI was 100% [95% confidence interval (CI): 87.2% to 100%], compared with 81.8% (CI: 67.3% to 91.8%) for CK-MB. Thus, cTnI was more sensitive than CK-MB mass for detection of myocardial injury in patients with small increases of total CK.

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