Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (856 page)

   CK is an enzyme that catalyzes the interconversion of ATP and creatine phosphate, controlling energy flow within cells, principally muscle. Its activity is greatest in striated muscle, heart tissue, and brain. The determination of CK activity is a proven tool in the investigation of skeletal muscle disease (muscular dystrophy) and is also useful in the diagnosis of myocardial infarction or stroke.

   
Normal range:

   Male: 49–348 IU/L

   Female: 38–206 IU/L

   Use

   Marker for injury or diseases of cardiac muscle with good specificity

   Measurement of choice for striated muscle disorders

   Interpretation

Increased In

   Necrosis or inflammation of cardiac muscle: disorders listed under CK-MB (CK index usually >4%)

   Necrosis, inflammation, or acute atrophy of striated muscle

   Disorders listed under CK-MB (CK index usually <4%)

   Muscular dystrophy

   Myotonic dystrophy