Apo A-1 comprises 60% to 70% of the protein content of HDL. Apo A-1 serves as an activator of LCAT which is involved in the transport of cholesterol from peripheral tissues to the liver where it is degraded. Decreased serum HDL cholesterol levels have been reported to correlate with increased risk of coronary artery disease (CAD); however, Apo A-1 has been suggested as a better discrimination of CAD than HDL. Apo A-1 levels also correlate with survival rates or risk factors for patients with myocardial infarction and peripheral vascular disease. Measurement of Apo A-1 may also aid in the diagnosis of Tangier disease (absence of alpha-lipoprotein).Patient must be fasting 12 to 14 hours.