A lipid profile typically measures the levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Dyslipidemia is the term that is used if lipid levels are outside the normal range. High levels of LDL cholesterol (the so-called “bad cholesterol”) greatly increase the risk for atherosclerosis because LDL particles contribute to the formation of atherosclerotic plaques. Low HDL levels ("good cholesterol") are an independent risk factor, because reverse cholesterol transport works to prevent plaque formation, or even cause regression of plaques once they have formed. HDL may also have anti-inflammatory properties that help reduce the risk of atherosclerosis. Fasting triglyceride levels are used to estimate the level of VLDL. High levels of triglycerides are also associated with an increased risk for atherosclerosis, although the mechanism is not entirely clear.