Test Details: Lipoproteins are a mixture of fat and protein that transport cholesterol in the blood to cells throughout the body. The two main groups of lipoproteins are called HDL (high-density lipoprotein) or "good" cholesterol and LDL (low-density lipoprotein) or "bad" cholesterol. Lipoprotein (a) is a type of LDL. Lipoprotein (a) particles are stickier than other types of LDL particles, so they may be more likely to cause blockages and blood clots in the blood vessels. As a result, high levels of lipoprotein may predispose an individual to higher risk for heart disease, stroke, and other serious conditions related to blockages in the vessels.