Cholesterol is a fatty substance necessary to produce hormones, to provide structure to cell membranes and to make bile acid needed to break down fats during digestion. High blood cholesterol is a significant risk factor for the onset of heart disease, the leading cause of death for men and women in the United States. To lower your risk for heart disease you must understand the types of cholesterol, the cholesterol ratio and its use for assessing your heart disease risk.
Types of Cholesterol
The liver produces approximately 75 percent of all the cholesterol in your body, according to the American Heart Association. To reach cells throughout the body, cholesterol must travel through the blood. Because cholesterol is waxy and blood is watery, cholesterol binds to specialized proteins, known as lipoproteins, that transport it through the bloodstream. Low-density lipoprotein, known as LDL, carries the majority of the cholesterol and keeps the cholesterol flowing through the blood vessels. High-density lipoprotein, HDL, carries only one-fourth to one-third of the cholesterol. Doctors refer to this type of cholesterol as "good" cholesterol because it picks up excess cholesterol and carries it to the liver, which breaks it down so it can be excreted from the body. Total cholesterol refers to the cholesterol reading that includes both LDL and HDL. Calculating the cholesterol ratio requires the total and HDL cholesterol levels.
High Cholesterol
As cholesterol levels increase due to an increased intake of dietary cholesterol or dietary fats or overproduction by the liver, the excess LDL cholesterol can build up along the walls of the blood vessels. This process, known as atherosclerosis, causes blood vessels to become thick and hard and interferes with the flow of blood. High cholesterol is one of the major risk factors for the onset of heart disease. For this reason, doctors warn patients of the dangers of high cholesterol, classified as a total cholesterol level over 240 mg/dL or a LDL cholesterol over 160 mg/dL. All patients over the age of 20 should monitor their cholesterol levels, cholesterol ratio and heart disease risk by having their blood tested at least every five years.
Cholesterol Ratio
To determine your LDL cholesterol level, you must fast for 12 hours, meaning no food or drinks other than water for 12 hours prior to drawing the blood sample. Although doctors consider the LDL cholesterol level the most important for determining your risk for heart disease, typical non-fasting cholesterol screenings fail to provide reliable results. Routine cholesterol screening tests performed using non-fasting blood samples can determine your total cholesterol and HDL cholesterol levels. Doctors use these results to determine your cholesterol ratio by dividing your HDL result into your total cholesterol result.
Ratio Risk
You should maintain a cholesterol ratio as low as possible, because the higher the ratio, the higher the risk for heart disease. For example, if your total cholesterol measures at 200 mg/dL and your HDL at 50 mg/dL, your cholesterol ratio calculates to 4 to 1. As total cholesterol levels get into the high range, such as 250 mg/dL and the HDL drops -- which increases the risk for heart disease since HDL removes cholesterol from the blood -- to 40 mg/dL, the resulting ratio of 6.25 to 1 shows an increased risk. Doctors utilize the cholesterol ratio as a screening tool to assess heart disease risk, but for diagnosis and treatment plans they must perform an additional test to determine the absolute LDL cholesterol level.
