This is the most specific test for diagnosis, and rhabdomyolysis is diagnosed if serum CK levels are 5 times the upper limit of normal or >1000 IU/L.[2]Kodadek L, Carmichael Ii SP, Seshadri A, et al. Rhabdomyolysis: an American Association for the Surgery of Trauma Critical Care Committee clinical consensus document. Trauma Surg Acute Care Open. 2022;7(1):e000836.
https://tsaco.bmj.com/content/7/1/e000836
http://www.ncbi.nlm.nih.gov/pubmed/35136842?tool=bestpractice.com
[1]Poels PJ, Gabreels FJ. Rhabdomyolysis: a review of the literature. Clin Neuro Neurosurg. 1993 Sep;95(3):175-92.
http://www.ncbi.nlm.nih.gov/pubmed/8242960?tool=bestpractice.com
Levels have been shown to correlate with severity.