What is creatine kinase and why is it elevated in Pompe disease?
Creatine kinase (CK) is an enzyme that is produced in all muscles. When muscles are being broken down because of a muscle disease, CK goes into the blood stream. Therefore, measuring CK in the blood can be an indication of whether a person has muscle breakdown. CK can be high for many reasons. If a person runs a marathon, they will likely have a high CK for a little while afterward because they had some mild muscle breakdown by running so long. However, if a person has a high CK without exercising and has some muscle weakness, it may be because of a muscle disease.
In Pompe disease, the CK is elevated due to muscle breakdown and can be over 10 times the normal range (less than 200 UI/L). People with late onset Pompe disease (LOPD) can have normal CK, but around 95% of the time it is elevated. It is important to remember that CK can be elevated for many reasons other than Pompe disease (it can be a measure of a heart attack because the heart muscle is breaking down, for example).
Kishnani PS, Steiner RD, Bali D et al. Pompe disease diagnosis and management guideline. Genet Med 2006 8:267-88.
Pompe Disease - Patients & Families: Getting Diagnosed https://www.pompe.com/en/patients/getting-diagnosed/tests.aspx