THU0331 SKELETAL TROPONIN I A POSSIBLE NOVEL BIOMARKER FOR MANAGEMENT OF PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES

Background The current biomarkers for the diagnosis and monitoring of diseased and injured 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 certainty are needed. Skeletal troponin I (skTnI) is a promising new biomarker for injured and diseased skeletal muscle tissue. Although studies have reported that circulating skTnI levels are elevated in response to trauma, exercise and various muscular diseases (1), its clinical utility to serve as a diagnostic indicator has largely been unexplored. Objectives Our aim was to develop and validate a novel assay for skTnI, and to assess its clinical performance with idiopathic inflammatory myopathy (IIM) patients. Methods A two-step fluoroimmunoassay was used to analyze the levels of skTnI in samples from healthy reference individuals (n=125), trauma patients (n=151), and patients with IIM (n=94). Later, skTnI and CK levels in patients with IIM were compared according to their disease activity status (active, pre-active or stable). Results The limit of detection was 1.2 ng/ml, and the upper reference limit (90th percentile) was 5.4 ng/ml. The median skTnI concentrations were 更多