Plasma CK levels are useful in the diagnosing rhabdomyolysis, where levels > 1,000iu/L but can exceed >10,000iU/L. Serial measurements are useful to assess the extent of muscle damage and to monitor its progress.
CK levels over 6000U/L are associated with an increased risk of acute tubular necrosis. Other causes of raised CK include myocarditis, myositis, bowel ischaemia, myxoedema and neuroleptic syndrome.
CK is also used in infants with muscular dystrophy as an initial investigation. Less serious causes include: prolonged endurance running, prolonged immobility on a hard surface e.g. elderly patient after a fall found lying on the floor, after haematoma formation, post seizures and as a result of statin induced myalgia.
