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 ¹ (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 ¹ (Finsterer, 2010). Inflammatory markers like ESR and CRP may assist in identifying inflammatory myopathies or associated systemic inflammation ¹. Additionally, thyroid function tests are often recommended to exclude thyroid-related myopathies as part of the initial workup ¹. While genetic and autoimmune antibody panels are important in further characterisation, they are not first-line blood tests in the initial assessment ¹ (Finsterer, 2010).