The Creatine Kinase MB (CK-MB) test is a blood test used to measure the level of CK-MB, an enzyme found mainly in the heart muscle. When the heart muscle is damaged, such as during a heart attack, CK-MB is released into the bloodstream. The CK-MB test is used to help diagnose a heart attack and to monitor the effectiveness of treatment. Elevated CK-MB levels may indicate damage to the heart muscle, but other conditions such as strenuous exercise, trauma, and certain medications can also cause elevated levels. The CK-MB test is often performed in conjunction with other cardiac enzyme tests, such as troponin, to provide a more complete picture of heart function. The CK-MB test is a useful tool in the diagnosis and management of heart disease.