Cholesterol in the blood is normal. Cholesterol is needed to protect nerves, make cell membranes, and produce hormones, says FamilyDoctor.org. Cholesterol is made in the liver. The body is generally able to make enough cholesterol to support necessary functions. Cholesterol in the blood also comes from food, like eggs, meat and dairy products. Cholesterol cannot dissolve in blood, and must be transported by lipoproteins. The lipoproteins include high-density lipoproteins, or HDL, low-density lipoproteins, or LDL, and lipoprotein (a), explains the American Heart Association. The measurements of these cholesterol properties in the blood can indicate a heart disease risk.
Low-density Lipoprotein
Low-density lipoprotein is known as the bad cholesterol. LDL is the primary carrier of cholesterol in the blood. High amounts of LDL in the blood cause a buildup of plaque in the arteries. The plaque buildup leads to narrowing and hardening of the arteries, known as atherosclerosis. The narrowing can lead to blockage, causing a heart attack or stroke, explains FamilyDoctor.org, an online publication of the American Association of Family Physicians. The American Heart Association says an LDL level greater than 160 mg/dL indicates a greater risk of heart disease.
High-density Lipoprotein
High-density lipoprotein is known as the good cholesterol. HDL carries cholesterol away from the arteries and back to the liver where it is cleared from the body, reports the American Heart Association. HDL may also remove the excess plaque buildup from the arteries. A higher HDL number, 60 mg/dL or greater, indicates a reduced risk of heart disease, according to FamilyDoctor.org. The American Heart Association also cautions against low levels of HDL, less than 40 mg/dL in women and less than 50 mg/dL in men, saying low numbers indicate an increased risk of heart disease.
Lipoprotein (a)
Lipoprotein (a) is genetically similar to plasma LDL, according to the American Heart Association. People with elevated lipoprotein (a) levels, greater than 30 mg/dL, are at a greater risk for developing premature atherosclerosis, says Medline Plus, a publication of the National Institutes of Health. The exact mechanism of lipoprotein (a) is unclear, but it is theorized that lesions on the arteries interact with lipoprotein (a) causing an increase in the plaque buildup, explains the American Heart Association.
