Heart disease is the largest cause of death in the United States. According to the Heart, Lung and Blood Institute, one million Americans suffer heart attacks every year, and half a million people die from heart disease. Cholesterol is one of the biggest risk factors, so getting a cholesterol test can predict heart disease before its onset.
Definition
Cholesterol is a waxy lipid used as a structural component in cell membranes and a precursor molecule to hormones. It is transported through the blood by a molecule called a lipoprotein, which is a combination of a protein and lipid. The American Heart Association states that there are two types of lipoproteins that occur in the bloodstream. High density lipoproteins, or HDL, carry cholesterol away to the liver to be excreted. Low density lipoprotein, or LDL, carries cholesterol through the rest of the body. When too much LDL circulates through the blood, it can build up and narrow the arteries.
Significance
Total cholesterol is a bit of a misnomer as a risk factor because only LDL is truly considered "bad." In fact, the presence of HDL in the blood may actively reduce the chances of heart disease because many researchers believe that it can remove excess cholesterol from arterial plaque. In combination with low LDL, it is an excellent indicator of overall heart health.
Recommendations
In the United States, blood cholesterol is measured in a unit called milligrams per deciliter. This essentially measures the amount of cholesterol per volume of blood. You should aim for an HDL level of at least 50 or 60 mg/dL. Total cholesterol is a combination of the HDL and LDL that exists in the blood; a level below 200 mg/dL is most desirable.
Ratio
An excellent way to actually measure heart disease risk factors is to calculate a ratio of total cholesterol to HDL. According to Dr. Thomas Behrenbeck of the Mayo Clinic, a ratio of 4-to-1 is fine. If this ratio goes above 4-to-1, then it means that you have too much LDL in relation to HDL. Of course, a ratio of less than 4-to-1 is preferable, because it means that the proportion of HDL to LDL is higher.
Examples
Total cholesterol of 200 mg/dL and HDL of 50 mg/dL would place you directly at a ratio of 4-to-1. However, this ratio would also entail an LDL of 150 mg/dL, which is considered to be bordering on high. Total cholesterol of 180 mg/dL and HDL of 60 mg/dL would give you a 3-to-1 ratio and an LDL of 120 mg/dL, which is an ideal amount for a healthy individual who is not at risk for heart disease. If you do have a risk for heart disease, then you will need to go low enough so that your total LDL levels are below 100 mg/dL.
