How is your nephew? What symptoms are present? According toa study done by Tsutomu et al, high creatine kinase (CK) level without any other clinical findings is sometimes observed in children. Creatine kinase is localized to skeletal muscle, cardiac muscle, a smooth muscle, and brain. When these organs are disturbed, localized CK is released into blood. Conditions associated with high CK level, such as progressive muscular dystrophy, polymyositis, and hypothyroidism should also be ruled out. Take care and do keep us posted.