Hello CPK is found in the skeletal muscles, heart muscles and brain cells. Elevated CPK usually indicates muscle damage. Some of the causes of elevated CPK are polymyositis, dermatomyositis, viral infections and heart diseases like viral myocarditis.  In children sometimes massive elevation of CPK is seen due to myositis following severe influenza. Other cause in children is spinal muscular dystrophy.  Exact cause can be diagnosed only after a clinical exam.  If your pediatrician suspects that your child may have muscular dystrophy, she will likely begin by testing the creatine kinase (CK) level in his blood. This muscle enzyme is very high in children with muscular dystrophy. After finding a high CK level, your Pediatrician will likely do DNA testing to look for mutations in the gene that makes dystrophin, an important muscle protein. If this genetic testing is negative, then a muscle biopsy may be done to confirm the diagnosis of muscular dystrophy. Have a joint consultation with rheumatologist and pediatrician. Thanks