CK Isoenzymes (by electrophoresis for macro-CK)

General Information

Creatine Kinase (CK, CPK) is an enzyme found primarily in the heart and skeletal muscles, and to a lesser extent in the brain. Significant injury to any of these structures will lead to a measurable increase in CK levels. Elevations in CK are found in:

• Myocardial infarction
• Crushing muscular trauma
• Any cardiac or muscle disease, but not myesthenia gravis or multiple sclerosus
• Brain injury
• Hypothyroidism
• Hypokalemia

Once elevated, CK remains elevated for several days, if the injury is acute. If there is on-going injury, the CK will remain elevated indefinitely.

CK enzymes consist of two subunits, which can be either B (brain type) or M (muscle type). There are therefore three different isoenzymes: CK-MM (CK-3), CK-BB (CK-1) and CK-MB (CK-2). CK-BB is found mostly in the brain and lungs, CK-MB is found mostly in the heart while CK-MM is found mostly in skeletal muscle. Measurement of CK isoenzymes may therefore be used to differentiate between muscle or heart diseases where total CK is elevated. It will also detect macro CK.