Lipoprotein (a) is a type of LDL cholesterol. These lipoproteins carry cholesterol to the cells in your arteries. If you have high levels of LDL particles, cholesterol can build up in your arteries and form blockages called plaques. This condition is known as atherosclerosis or "hardening of the arteries." It can lead many serious medical conditions including strokes, heart disease, peripheral vascular disease, and kidney disease.