A concise description of four important lipoproteins is given below.
- Chylomicrons: These are the least dense of the lipoproteins. They have a high amount of lipid and transport triglycerides and cholesterol from the intestine to the tissues of the body.
- Very low density lipoprotein (VLDL): These lipoproteins carry liver-made triglyceride to the tissues of the body. They are denser than chylomicrons.
- Low density lipoprotein (LDL): These lipoproteins deliver cholesterol to peripheral cells. They are denser than chylomicrons and VLDL.
- High density lipoprotein (HDL): These lipoproteins pick up cholesterol accumulating in blood vessels and deliver it to the liver and steroid-producing tissues. They are the densest of the lipoproteins, as they contain a high amount of protein and a smaller amount of lipids.
HDL and LDL are very commonly measured lipoproteins in the clinical laboratory due to their important and opposite biological functions. Patients and the public often refer to HDL cholesterol as "good cholesterol," as it removes cholesterol from blood vessel walls and returns it to the liver for other uses. In fact, high serum levels of HDL are associated with a decrease in the risk of atherosclerosis.
Conversely, LDL cholesterol is often referred to as "bad cholesterol," as it delivers cholesterols to cells where it is stored and accumulates.
