Apolipoprotein A1 (ApoA1), a major component of high-density lipoproteins, acts as an acceptor for sequential transfers of phospholipids and free cholesterol from peripheral tissues and transports cholesterol to the liver and other tissues for excretion and steroidogenesis. Serum ApoA1 levels are inversely related to the risk of developing atherosclerosis. Decreased ApoA1 levels have also been associated with Tangier disease, familial hypolipoproteinemia, and systemic non-neuropathic amyloidosis. Cayman's ApoA1 (human) ELISA Kit is a competitive assay that can be used to measure ApoA1 in plasma and serum without prior sample purification. Normal human plasma and serum levels of ApoA1 range from 0.9-2.0 mg/ml. The assay has a range from 0.078-10 μg/ml and a sensitivity (80% B/B0) of approximately 0.2 μg/ml.