The Apolipoprotein A1 (Apo-A1) test measures the level of Apo-A1, a protein component of high-density lipoprotein (HDL), often referred to as “good cholesterol.” Apo-A1 plays a key role in cholesterol metabolism and helps remove excess cholesterol from the bloodstream, thereby reducing the risk of cardiovascular disease. Low levels of Apo-A1 are associated with an increased risk of heart disease and atherosclerosis. This test is used to assess heart disease risk, especially in conjunction with other lipid profile tests. A blood sample is required for this test.