Cholesterol numbers indicate the amount of cholesterol in the bloodstream (cholesterol is a waxy, fat-like substance manufactured in the liver and found in all tissues). For humans, a total cholesterol number above 200 means there is an increase in the risk of heart disease (between 200 and 239 is considered borderline high cholesterol); for anything below 200, there is less of a risk for heart disease.

But total cholesterol is not the only number to know. There is also Low Density Lipoprotein (LDL), or “bad” cholesterol. LDL is the main source of the buildup and blockage in the arteries (risk levels are above 130, measured in milligrams per decaliter). There is also High Density Lipoprotein (HDL), the “good” cholesterol that helps keep the plaque from building up (risk levels are below 40, measured in milligrams per decaliter).

When there is too much cholesterol in the blood, it can build up on the walls of the arteries. Over time, the buildup (often called plaque) causes “hardening of the arteries,” or a narrowing of the arteries that restricts or stops blood flow to the heart. Blood carries oxygen to the heart, and if there is less blood (and thus, less oxygen) reaching the heart, chest pain can result. If there is a near-complete or complete blockage that cuts off the blood supply to a portion of the heart, a heart attack (myocardial infarction) is often the result. This is why most doctors recommend watching your numbers for total cholesterol, HDL, and LDL for signs of any change.