Jochen Jarausch

Analytical Validation of a High-Sensitivity Cardiac Troponin T Assay

BACKGROUND We report the development of a novel high-sensitivity cardiac troponin T (hs-cTnT) assay, a modification of the Roche fourth-generation cTnT assay, and validation of the analytical performance of this assay. METHODS Validation included testing of analytical sensitivity, specificity, interferences, and precision. We established the 99th percentile cutoff from healthy reference populations (n = 616). In addition, we studied differences in time to a positive result when using serial measurements of hs-cTnT vs cTnT in patients with a confirmed diagnosis of non-ST elevation myocardial infarction (non-STEMI). RESULTS The hs-cTnT assay had an analytical range from 3 to 10 000 ng/L. At the 99th percentile value of 13.5 ng/L, the CV was 9% using the Elecsys 2010 analyzer. The assay was specific for cTnT without interferences from human cTnI or cTnC, skeletal muscle TnT, or hemoglobin concentrations up to 1000 mg/L, above which falsely lower values would be expected. When the assay was evaluated clinically, a hs-cTnT higher than the 99th percentile concentration identified a significantly higher number of patients with non-STEMI on presentation (45 vs 20 patients, P = 0.0004) compared with cTnT, and a final diagnosis of non-STEMI was made in 9 additional patients (55 vs 46 patients, P = 0.23) after serial sampling. Time to diagnosis was significantly shorter using hs-cTnT compared with cTnT [mean 71.5 (SD 108.7) min vs 246.9 (82.0) min, respectively; P < 0.01]. CONCLUSIONS The analytical performance of hs-cTnT complies with the ESC-ACCF-AHA-WHF Global Task Force recommendations for use in the diagnosis of MI.

Multicenter analytical evaluation of a high-sensitivity troponin T assay.

BACKGROUND High-sensitivity cardiac troponin assays are being introduced clinically for earlier diagnosis of acute myocardial infarction (AMI). We evaluated the analytical performance of a high-sensitivity cardiac troponin T assay (hscTnT, Roche Diagnostics) in a multicenter, international trial. METHODS Three US and 5 European sites evaluated hscTnT on the Modular® Analytics E170, cobas® 6000, Elecsys 2010, and cobas® e 411. Precision, accuracy, reportable range, an inter-laboratory comparison trial, and the 99th percentile of a reference population were assessed. RESULTS Total imprecision (CVs) were 4.6-36.8% between 3.4 and 10.3 ng/L hscTnT. Assay linearity was up to 10,000 ng/L and the limit of blank and detection were 3 and 5 ng/L, respectively. The 99th percentile reference limit was 14.2 ng/L (n=533). No significant differences between specimen types, assay incubation time, or reagent lots existed. A substantial positive bias (76%) exists between the 4th generation and hscTnT assays at the low end of the measuring range (<50 ng/L). hscTnT serum pool concentrations were within 2SD limits of the mean of means in the comparison trial, indicating comparable results across multiple platforms and laboratories. CONCLUSION The Roche hscTnT assay conforms to guideline precision requirements and will likely identify additional patients with myocardial injury suspicious for AMI.

Clinical value of the first automated TSH receptor autoantibody assay for the diagnosis of Graves’ disease (GD): an international multicentre trial

Background  Most recently, a new rapid and fully automated electrochemiluminescence immunoassay for the determination of TSH receptor autoantibodies (TRAb) based on the ability of TRAb to inhibit the binding of a human thyroid‐stimulating monoclonal antibody (M22) has been established.

Preanalytical Storage Does Not Affect 99th Percentile Cardiac Troponin T Concentrations Measured with a High-Sensitivity Assay

To the Editor: On the occasion of the introduction of the high-sensitivity cardiac troponin T (hs-cTnT)1 (fifth-generation) assay from Roche Diagnostics and considering the importance of a stable 99th percentile upper reference limit for early diagnosis of acute myocardial infarction (1), we evaluated the impact of various preanalytical storage conditions on cTnT concentrations around the 99th percentile (14 ng/L). The stability of cTnT as measured with the fifth-generation hs-cTnT assay has previously been shown (2, 3); however, the storage conditions and cTnT concentrations evaluated in these studies were limited. In this study, we investigated the most common routine storage conditions for whole blood, serum, and heparin-treated plasma. We obtained samples from 90 patients admitted to the catheterization laboratory for suspected minor myocardial damage. We used multiple samples from individual patients instead of pooled serum to prevent masking of possible matrix effects and to study a wider range of cTnT concentrations. Approval was given by the Medical Ethical Committee of Amphia Hospital, Breda, the Netherlands. All subjects gave written informed consent. For evaluating the effect of storage of whole blood, we collected venous blood from 30 participants into 3 serum tubes each (10-mL Venosafe™ Plastic Tubes, Serum Gel; Terumo) and 3 …