Cholesterol is a waxy, fat-like substance that is found in all cells of the body. Cholesterol travels through your bloodstream on packages called lipoproteins. There are two kinds of lipoproteins that carry cholesterol throughout the body: LDL (low-density lipoproteins) and HDL (high-density lipoproteins).
What are LDL and HDL?
LDL cholesterol is called "bad" cholesterol. A high LDL level causes buildup of cholesterol through your arteries. HDL cholesterol is called "good" cholesterol. This is because it carries cholesterol from other parts of your body back to your liver. The liver then removes the cholesterol from your body.
LDL and HDL Structural and Functional Difference
The main structural difference between LDL ad HDL is their compositions. Approximately 50% of the weight of an LDL particle is cholesterol and only 25% is protein. HDL particles, on the other hand, consist of 20% cholesterol by weight and 50% protein. Both LDL and HDL proteins transport cholesterol in the blood, but the main functional difference between the two is they deliver cholesterol to different parts of the body. LDL takes cholesterol to the cells and HDL takes cholesterol to the liver to be disposed of.
Why do doctors monitor the concentrations of LDL and HDL in patients' blood?
LDL and HDL are monitored during a blood test because they are used to help decrease the patient's risk of heart disease.
Concentrations of LDL and HDL Associated with Heart Disease
Other Monitored Molecules
- Total Cholesterol