Cholesterol is a chemical that has a number of functions, both good and bad, in the human body. Cholesterol is an important part of the cell membrane and is also used by the body to make steroids, which are important chemical signals. However, cholesterol can also build up on artery walls, leading to atherosclerosis and cardiovascular disease.
Identification
Serum cholesterol is a measure of the concentration of cholesterol that is present in the blood. It is typically measured in terms of milligrams per deciliter. As the American Heart Association explains, it is often used to screen patients for their risk of developing cardiovascular disease, although this test does not distinguish between different forms of cholesterol.
Test Procedure
Lab Tests Online notes that serum cholesterol levels are measured using a blood sample. Usually, the blood sample is obtained from an arm vein, though it can also be obtained by pricking a finger (also known as a finger stick) if the blood is to be tested using a small portable device. Otherwise, the blood sample is sent to a laboratory, which will then measure the amount of cholesterol in the blood.
Levels
The American Heart Association indicates that serum cholesterol levels below 200 milligrams per deciliter are optimal. Serum cholesterol levels between 200 and 239 milligrams per deciliter are considered to be borderline high, and anything above 240 milligrams per deciliter puts a patient at a high risk of developing cardiovascular disease. Patients with high or borderline high serum cholesterol levels may need to have a lipid profile done to determine the levels of the different kinds of cholesterol.
Types
One important aspect of cholesterol is that it does not travel by itself in the blood. It instead is bound up into lipid/protein combinations called lipoproteins. There are many different kinds of lipoproteins, and some of them can actually protect the cardiovascular system. High density lipoprotein (HDL) is also known as the "good" cholesterol because high levels of it are correlated with good cardiovascular health, whereas low density lipoprotein (LDL) is correlated with poor cardiovascular health. As a result, although overall serum cholesterol measurements can be used to measure a person's risk of developing heart disease, they do not tell the whole story.
Considerations
Medline notes that a number of factors can artificially elevate or depress your total cholesterol levels. Certain drugs (including birth control pills, corticosteroids and beta-blockers) can cause your serum cholesterol to be unusually high, whereas other medications (including MAO inhibitors and some gout medications) can artificially lower your cholesterol levels. Recent illnesses (including a flare-up of arthritis) can also raise or lower your cholesterol measurements.
