A 20-year-old male presents to the ED with complaints of malaise, nausea, and dark urine after he started a cross fit for the last 5 days. Vitals signs are as follows: T 98 F, HR 120, BP 110/70, RR 20, and SpO2 98% on RA. Patient appears fatigued with diffuse muscle soreness but soft compartments. Patient has a UA sent which shows 2+ blood. What is the next most important test to assist with direct management of this patient? 

A. EKG

B. Creatine Kinase 

C. Calcium Levels

D. Urine microscopy 

A. EKG. A specific CK level does not define rhabdomyolysis. But if CK >5 times the upper limit of normal (varies for different labs) then it is indicative of rhabdomyolysis. However, hyperkalemia is a the most concerning complication and therefore EKG changes indicative of hyperkalemia is the most important next step. 

 Scalo, R  et al. (2015). Rhabdomyolysis: A genetic perspective. Orphanet Journal of Rare Disease, 10 (15). 02 May 2015. <https://ojrd.biomedcentral.com/articles/10.1186/s13023-015-0264-3>.

For a deeper dive on rhabdomyolysis, please refer to our old post: http://emdaily.cooperhealth.org/content/emconf-rhabdomyolysis