Cardiovascular disease is the largest killer of Americans and accounts for approximately 960,000 deaths each year. At least 50 million U.S. adults have levels of cholesterol in their blood that require medical advice and treatment. As the world reference laboratory for measuring cholesterol, triglycerides, high-density lipoproteins, and low-density lipoprotein cholesterol, CDC's Lipid Reference Laboratory helps to ensure the quality of over 300 million cholesterol measurements made in the United States alone each year. With accurate measurements, doctors can diagnose and properly treat people with high cholesterol levels, thus reducing illness and death associated with this disease. Additionally, the laboratory standardizes lipid measurements for domestic and international laboratories that together are involved in ongoing epidemiologic studies or clinical trials investigating risk factors for cardiovascular disease. By serving as the accuracy base for lipids and lipoproteins, CDC's Lipid Reference Laboratory ensures the compatibility of results obtained from these investigations.