Creatine Kinase (CK), also known as creatine phosphokinase (CPK), is an enzyme that plays a critical role in energy metabolism within cells, particularly in muscle cells. CK catalyzes the conversion of creatine and uses adenosine triphosphate (ATP) to create phosphocreatine (PCr) and adenosine diphosphate (ADP). This reaction is vital for the rapid regeneration of ATP in tissues with high energy demands, such as the skeletal muscle, heart, and brain. Elevated levels of creatine kinase in the blood are often indicative of muscle damage, as CK leaks out of damaged or stressed muscle cells into the bloodstream. Conditions leading to increased CK levels include muscle diseases (myopathies), vigorous exercise, myocardial infarction (heart attack), and strokes. Testosterone therapy can influence creatine kinase levels, as testosterone has anabolic effects that promote muscle growth and recovery. Studies have shown that testosterone can affect muscle protein synthesis and repair, potentially leading to changes in CK levels. Monitoring CK levels in patients undergoing testosterone therapy can provide insights into muscle health and metabolism, helping to assess the physiological impact of the treatment and identify any adverse effects related to muscle damage or stress.