MB and rhabdomyolysis: In rhabdomyolysis, serum creatine kinase (CK) is elevated (>5× the upper limit of normal or >1,000 U/L) along with elevated serum myoglobin, lactate dehydrogenase potassium, creatinine, aspartate aminotransferase, alanine aminotransferase, and urine myoglobin [11]. The increase in serotonin levels caused by MDMA use not only directly triggers rhabdomyolysis but also causes hyperpyrexia, muscle stiffness, and hyperreflexia.