LDL Cholesterol test measures the level of LDL cholesterol in blood. LDL is often referred to as bad cholesterol. This is because too much LDL causes a build-up of cholesterol in your arteries, which can lead to heart attacks and strokes. According to the National Heart, Lung, and Blood Institute, adults should have an LDL test at least once every five years. It is a part of Lipid Profile. It is always advisable to go for complete profile, as level of each test in profile are considered while making decision on diagnosis as well as monitoring the treatment.