Assessment of patients with idiopathic inflammatory myopathies and isolated creatin-kinase elevation

Idiopathic inflammatory myopathies (IIM) are a group of diseases characterized by inflammation of the skeletal muscle. Weakness, mainly affecting the proximal muscles, is the cardinal muscular symptom in IIM. In patients with dermatomyositis, peculiar skin lesions are observed. The assessment of patients with IIM includes clinical and laboratory evaluation, and clinimetric measurements. Different tools have been proposed to measure muscular and extramuscular disease activity and damage in patients with IIM. A core set of measurements to use in clinical practice was recently proposed. Among laboratory features the increase of serum creatine kinase (CK) is considered a hallmark of muscle inflammation/damage. However, subjects with persistent CK elevation, without any evidence of a definite myopathy, are often seen in clinical practice and need a careful assessment. Indeed, CK blood levels can also increase in non-myopathic conditions, e.g. in case of intense physical exercise, assumption of some drugs (statins), muscular dystrophy, muscular trauma or in case of neuro-muscular disorders which all should be considered in the diagnostic work-up. The assessment of patients with IIM and hyperCKemia will be discussed in this paper.