Cholesterol is an important lipid for the body, because it is a part of cell membranes and can also be used to make certain kinds of hormones known as steroid hormones. Cholesterol in the blood, however, can result in cardiovascular disease. High LDL levels mean that a person has a high concentration of one particular form of cholesterol, which is especially dangerous.

Lipoproteins

When cholesterol is in the blood, it is packaged into complexes known as lipoproteins. Lipoproteins are made by the liver and are made of cholesterol, proteins and triglycerides, which are another form of lipid. Lipoproteins are needed for cholesterol to travel in the blood because lipids do not mix well with the aqueous environment of the blood.

Low-Density Lipoprotein

Low-density lipoprotein, which is also known as LDL, is one type of lipoprotein. Low-density lipoprotein is also known as the "bad" cholesterol, because this lipoprotein can cause cholesterol to become deposited in the walls of the arteries. When cholesterol gets deposited in the walls of the arteries, the arteries become stiff and narrow. If this happens in the coronary arteries, they can become blocked, leading to decreased blood flow and a heart attack, the American Heart Association explains.

Test

Low-density lipoprotein levels in the blood are usually measured as part of a test known as a lipid profile, LabTestsOnline reports. This blood test measures the levels of LDL cholesterol and triglycerides, which can lead to heart disease, as well as another type of lipoprotein known as high-density lipoprotein or HDL. HDL can prevent cholesterol from building up in the walls of the arteries because it works as a cholesterol scavenger.

Levels

Ideally, LDL cholesterol levels are less than 100 milligrams per dL of blood, LabTestsOnline explains. Between 130 and 159 milligrams per dL of blood is considered to be borderline high. Levels between 160 and 189 milligrams per dL of blood is classified as high, and anything above that is considered to be very high.

Reducing LDL

Patients who have high LDL can lower it in a number of ways. A healthy diet which is low in saturated fat and cholesterol can help lower LDL levels, the National Heart Lung and Blood Institute explains. Losing excess weight and getting regular exercise can also lower LDL levels in most patients. There are also many different prescription medications which can lower LDL levels.