About 20-30% of Active Dermatomyositis patients may have normal muscle enzyme level. Also, sometimes muscle enzymes other than CK and aldolase are elevated such as LDH, AST and ALT. So check all 5 muscle enzymes. Can also do EMG or MRI or muscle biopsy to confirm muscle involvement.  First lin...

Patients with dermatomyositis can have normal muscle enzymes even in the presence of muscle involvement noted by imaging or biopsy. Therefore, in a patient with skin-biopsy-proven DM and proximal muscle weakness, I would start treatment with either methotrexate or azathioprine and consider other age...