Creatine kinase (CK) is an enzyme found in the heart, brain, and skeletal muscles. High levels of CK can indicate damage to these tissues, such as after a heart attack or muscle injury.
Acetylcarnitine, synthesized from carnitine and acetyl-CoA, helps maintain mitochondrial function. Skeletal muscle injury associated with elevated CK could disrupt acetylcarnitine metabolism.
Carnitine helps transport fatty acids into mitochondria for energy production in skeletal muscle. Muscle damage or disease marked by high CK levels may impair carnitine utilization and increase circulating carnitine.
Muscaritoli M, Guida S, Barrea L, Capuano A, Gnoni A, Colao A, Squadrito F. Creatine, L-Carnitine, and ω3 Polyunsaturated Fatty Acid Supplementation in Sports: A Systematic Review. Nutrients (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163371/
Sugino K, Nakamura T, Kubota S, et al.. Alteration of the serum myostatin level following L-carnitine treatment in patients with chronic obstructive pulmonary disease. International Journal of Functional Nutrition (2020). https://www.spandidos-publications.com/10.3892/ijfn.2020.4
Creatinine is formed from the breakdown of creatine phosphate in muscle. Increased creatine kinase levels indicate muscle damage or disease and will elevate blood creatinine levels.
Henry J. Vander, Joann S. Airhart, J. Cesar Cabrera, John E. Gerlt, Roger M. Freeman. Creatinine Kinase - Clinical Methods - NCBI Bookshelf. NCBI Bookshelf (2022). https://www.ncbi.nlm.nih.gov/books/NBK352/
Lactic acid builds up when oxygen is limited, such as during intense exercise or with muscle damage. Elevated CK and lactate together can indicate muscle injury or disease.
Miyamoto, T., Oguma, Y., Sato, Y., et al.. Elevated Creatine Kinase and Lactic Acid Dehydrogenase and Decreased Osteocalcin and Uncarboxylated Osteocalcin are Associated with Bone Stress Injuries in Young Female Athletes. Scientific Reports (2018). https://doi.org/10.1038/s41598-018-36982-0
Styrkarsdottir U., et al.. Common and rare variants associating with serum levels of creatine kinase and lactate dehydrogenase. Nature Communications (2016). https://www.nature.com/articles/ncomms12263
