Department of Biochemistry/Biotechnology, University of Turku, Turku, Finland.
Intensive Care Medicine and Pain Management, Turku University Hospital, Turku, Finland.
J Appl Lab Med. 2020 Mar 1;5(2):320-331. doi: 10.1093/jalm/jfz016.
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).
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).
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 <limit of detection (LoD), 2.7 ng/mL, and 8.6 ng/mL in reference, trauma, and IIM cohorts, respectively. Differences in measured skTnI levels were statistically significant between all three study cohorts (Kruskal-Wallis P < 0.001; Mann-Whitney P < 0.001 for all). skTnI and CK had a strong positive correlation (Spearman's r = 0.771, P < 0.001), and the longitudinal changes in skTnI mirrored those observed with CK.
With the skTnI assay, patients with IIM were identified from healthy individuals and from patients with traumatic muscular injuries. When compared to CK, skTnI appeared to be more accurate in managing patients with low-grade IIM disease activities. The developed assay serves as a reliable analytical tool for the assessment of diagnostic accuracy of skTnI in the diagnosis and monitoring of myopathies.
目前用于诊断和监测受损和患病骨骼肌的生物标志物，如肌酸激酶（CK），具有有限的组织特异性，并且无法区分病理和生理变化。因此，需要新的具有更高诊断准确性的生物标志物。我们的目的是开发和验证一种新型的骨骼肌肌钙蛋白 I（skTnI）检测方法，并评估其在特发性炎性肌病（IIM）患者中的临床性能。
采用两步荧光免疫分析法分析健康参考个体（n=140）、创伤患者（n=151）和 IIM 患者（n=61）的样本。
检测限为 1.2ng/mL，90 百分位上限（90th 百分位）为 5.2ng/mL。skTnI 浓度的中位数在参考组、创伤组和 IIM 组分别为<检测限（LoD），2.7ng/mL 和 8.6ng/mL。三组研究队列之间测量的 skTnI 水平差异具有统计学意义（Kruskal-Wallis P<0.001；Mann-Whitney P<0.001 均为 P<0.001）。skTnI 和 CK 具有很强的正相关性（Spearman's r=0.771，P<0.001），skTnI 的纵向变化与 CK 观察到的变化一致。
通过 skTnI 检测，我们能够从健康个体和创伤性肌肉损伤患者中识别出 IIM 患者。与 CK 相比，skTnI 在管理低级别 IIM 疾病活动的患者方面似乎更准确。所开发的检测方法可作为评估 skTnI 在肌病诊断和监测中的诊断准确性的可靠分析工具。
