Serum creatinine kinase (CK) level varies with age, gender, race and physical activity. For these reasons there is no normal serum CK level. Many pathological situations cause hyperCKemia, such as neuromuscular disorders (muscular dystrophy, inflammatory myositis, mitochondrial myopathy) and multiple systemic causes. The diagnostic approach to pauci or asymtomatic hyperCKemia can therefore be difficult and lead to multiple, and sometimes invasive tests, such as muscle biopsy. This study aims to describe the diagnoses associated with persistent elevation of serum creatine kinase and to precise the role of the muscule biopsy.

Inclusion Criteria:

• patients hospitalised in a ward of internal medicin
• having a persistent elevation of serum creatine kinase >3 times the upper normal laboratory value, repeated for 2 times

Exclusion Criteria:

• known neuro-muscular disease causing elevation of creatine kinase
• evident post-traumatic cause responsible for the elevation of creatine kinase
• incomplete medical records

Patients hospitalised in the ward of internal medicin of Nancy University Hospital or UNEOS General Hospital of Metz between 2009 and 2018.