(lipoproteins, ldl) A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.

(low density lipoprotein) A lipoprotein that carries cholesterol around the body, for use by various cells. LDL transports cholesterol to the arteries and increased levels are associated with atherosclerosis, and thus myocardial infarctions and strokes. This is why cholesterol inside LDL lipoproteins is called bad cholesterol.

(low density lipoprotein) Class of lipoproteins responsible for transport of cholesterol to extrahepatic tissues; they are formed in the circulation when very-low-density lipoproteins are degraded first to intermediate-density lipoproteins and then to LDL by the gain and loss of specific apolipoproteins and the loss of most of their triglycerides; LDL are taken up and catabolized by both the liver and extrahepatic tissues by specific receptor-mediated endocytosis.

So-called bad cholesterol. If there is too much LDL in the blood, it can collect on artery walls, narrowing them and making heart attacks and strokes more likely.

(ldl: the "bad" cholesterol) Cholesterol is a waxy, fat-like substance that's found in all the cells in your body. Your liver makes cholesterol, and it is also in some foods, such as meat and dairy products. Your body needs some cholesterol to work properly. But having too much cholesterol in your blood raises your risk of coronary artery disease. LDL and HDL are two types of lipoproteins. They are a combination of fat (lipid) and protein. The lipids need to be attached to the proteins so they can move through the blood. LDL and HDL have different purposes: LDL stands for low-density lipoproteins. It is sometimes called the "bad" cholesterol because a high LDL level leads to a buildup of cholesterol in your arteries.; HDL stands for high-density lipoproteins. It is sometimes called the "good" cholesterol because it carries cholesterol from other parts of your body back to your liver. Your liver then removes the cholesterol from your body. If you have a high LDL level, this means that you have too much LDL cholesterol in your blood. This extra LDL, along with other substances, forms plaque. The plaque builds up in your arteries; this is a condition called atherosclerosis. Coronary artery disease happens when the plaque buildup is in the arteries of your heart. It causes the arteries to become hardened and narrowed, which slows down or blocks the blood flow to your heart. Because your blood carries oxygen to your heart, this means that your heart may not be able to get enough oxygen. This can cause angina (chest pain), or if the blood flow is completely blocked, a heart attack. A blood test can measure your cholesterol levels, including LDL. When and how often you should get this test depends on your age, risk factors, and family history. The general recommendations are: For people who are age 19 or younger:: The first test should be between ages 9 to 11; Children should have the test again every 5 years; Some children may have this test starting at age 2 if there is a family history of high blood cholesterol, heart attack, or stroke. For people who are age 20 or older:: Younger adults should have the test every 5 years; Men ages 45 to 65 and women ages 55 to 65 should have it every 1 to 2 years. For people who are older than 65: They should have the test every year. You may need to get your cholesterol checked more often if you have heart disease, diabetes, or a family history of high cholesterol. Things that can affect your LDL level include: Diet. Saturated fat and cholesterol in the food you eat make your LDL level rise; Weight. Being overweight tends to raise your LDL level, lower your HDL level, and increase your total cholesterol level; Physical Activity. A lack of physical activity can lead to weight gain, which can raise your LDL level; Smoking. Cigarette smoking lowers your HDL cholesterol. Since HDL helps to remove LDL from your arteries, if you have less HDL, that can contribute to you having a higher LDL level.; Age and Sex. As women and men get older, their cholesterol levels rise. Before the age of menopause, women have lower total cholesterol levels than men of the same age. After the age of menopause, women's LDL levels tend to rise.; Genetics. Your genes partly determine how much cholesterol your body makes. High cholesterol can run in families. For example, familial hypercholesterolemia (FH) is an inherited form of high blood cholesterol.; Medicines. Certain medicines, including steroids, some blood pressure medicines, and HIV medicines, can raise...