ABSTRACT
BACKGROUND: The current biomarkers for diagnosis and monitoring of injured and diseased skeletal muscles, such as creatine kinase (CK), have limited tissue specificity and incapability to differentiate between pathological and physiological changes. Thus, new biomarkers with improved diagnostic accuracy are needed. Our aim was to develop and validate a novel assay for skeletal troponin I (skTnI), and to assess its clinical performance in patients with idiopathic inflammatory myopathies (IIM). METHODS: A two-step fluoroimmunoassay was used to analyze samples from healthy reference individuals (n = 140), patients with trauma (n = 151), and patients with IIM (n = 61). RESULTS: The limit of detection was 1.2 ng/mL, and the upper reference limit (90th percentile) was 5.2 ng/mL. The median skTnI concentrations were Subject(s)
Biomarkers
, Myositis/blood
, Myositis/diagnosis
, Troponin I/blood
, Adult
, Aged
, Biological Assay/methods
, Biological Assay/standards
, Female
, Fluoroimmunoassay/methods
, Fluoroimmunoassay/standards
, Humans
, Male
, Middle Aged
, Muscle, Skeletal/metabolism
, Muscle, Skeletal/pathology
, Myositis/etiology
, Reproducibility of Results
, Sensitivity and Specificity
, Young Adult
ABSTRACT
BACKGROUND: Whereas elevated cardiac troponin (cTn) concentrations i.e. above the 99th percentile of healthy reference population (recommended cutoff for the diagnosis of myocardial infarction) are well-documented in healthy individuals after prolonged and/or intensive exercises such as marathons, data on less-strenuous sports are scarce. Therefore, our aim was to investigate cTnI and cTnT release in response to recreational resistance training, here a single-bout of 1-h kettlebell workout. METHODS: Serum samples were collected from 11 apparently healthy volunteers the previous day (pre-exercise), three hours after the kettlebell class (post-exercise), the next day and three days later. The aliquoted samples were analyzed with Abbott Laboratories' Architect high-sensitivity (hs)-cTnI assay (limit of detection, LoD = 2 ng/L), our 3+1-type cTnI assay free from cTn-specific autoantibody interference (LoD = 3 ng/L) and Roche Diagnostics' hs-cTnT assay (LoD = 5 ng/L). RESULTS: The post-exercise cTn concentrations were significantly higher than the pre-exercise values (median 5.5-9.6 ng/L vs.