One way to check for good health is to measure the amount of the various types of cholesterol in the blood. Unlike some tests, however, normal cholesterol levels are not always the same for all people. There are optimal or desirable levels of cholesterol in a general sense, but these levels are not realistically achievable by all people at all times, sometimes due to mitigating medical conditions or lifestyle factors. While there are variations in normal cholesterol levels, there are still notable extremes where cholesterol is simply too high and poses a health risk despite what the normal level would be. The most effective tests for cholesterol measure three separate types of cholesterol in the blood, the combination of which gives an overall score that is somewhat less effective for determining the exact state of health. High density lipoproteins (HDL), low density lipoproteins (LDL), and triglycerides each serve a different function in the body, and have individual levels that are considered normal. Measurements are generally made in milligrams per deciliter (mg/dL) of blood. When combined, the three measurements constitute the total cholesterol level, and when the amount of HDL is divided into the total score, the cholesterol ratio is calculated. For a normal, healthy human that is over the age of 20 and that has not eaten for 12 hours or more prior to testing, a normal overall cholesterol score would be less than 200 mg/dL. When broken down into the three component parts, normal cholesterol levels are indicated as an LDL level of less than 100 mg/dL, an HDL level of over 40 mg/dL, and a triglyceride count of less than 150 mg/dL. A normal cholesterol ratio would be 4:1 or lower. Some factors affect what is considered normal, however. Women tend to have a higher average level of HDL, with the normal range being between 50-60 mg/dL, while men normally test between 40-50 mg/dL. Preexisting medical conditions, a previous heart attack or stroke, and even age can increase the normal cholesterol levels. This is primarily because the body is unable to fully process cholesterol for some reason, leading to naturally elevated levels of cholesterol in the blood. The health risks of the higher average level of cholesterol are still the same, regardless of medical conditions.