Which blood tests are most useful in the initial assessment of myopathy?

In the initial assessment of a patient presenting with suspected myopathy, the most useful blood tests include serum creatine kinase (CK), liver function tests (particularly alanine aminotransferase [ALT] and aspartate aminotransferase [AST]), and inflammatory markers such as erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Serum CK is the primary and most sensitive marker for muscle damage and is typically elevated in myopathies, making it essential for initial evaluation NICE CG95 Finsterer 2010. Liver enzymes ALT and AST can be elevated due to muscle injury rather than liver pathology and thus help support the diagnosis of muscle disease NICE CG95 Finsterer 2010. Inflammatory markers like ESR and CRP may assist in identifying inflammatory myopathies or associated systemic inflammation NICE CG95. Additionally, thyroid function tests are often recommended to exclude thyroid-related myopathies as part of the initial workup NICE CG95. While genetic and autoimmune antibody panels are important in further characterisation, they are not first-line blood tests in the initial assessment NICE CG95 Finsterer 2010.