Cholesterol is a fatty substance your body needs to build healthy cells, produce vitamin D and manufacture certain hormones. Blood serum is the watery part of your blood that's left over when your blood is spun in the laboratory to create a clot. A blood serum cholesterol test measures the amount of specific types of cholesterol in your blood serum.
Identification
A blood serum cholesterol test measures several types of cholesterol. Cholesterol's waxy consistency prevents it from dissolving well in the blood, so it travels around your body attached to lipoproteins. High-density lipoprotein, or HDL, is known as the "good" cholesterol. Low-density lipoprotein, or LDL, is the "bad" cholesterol. Total cholesterol is a combination of HDL, LDL, a genetic variant of LDL known as Lp(a) and fats called triglycerides.
Functions
When LDL and total cholesterol levels are high, excess LDL cholesterol and fats accumulate inside the walls of the arteries that nourish your heart. Over time, these accumulations turn into hard plaques that narrow the diameter of the arteries and make them more rigid. Your heart is deprived of the oxygen and other nutrients it needs for optimal function, and you have coronary heart disease. HDL cholesterol helps carry extra LDL cholesterol to the liver so it can be removed from your body and may also pull cholesterol from the plaques, says the American Heart Association.
Goals
The National Heart, Lung and Blood Institute Adult Treatment Panel III published consensus guidelines about blood serum cholesterol levels in 2001. You should keep your total cholesterol below 200 mg/dL, understand that readings between 200 and 239 mg/dL are borderline high, and that 240 mg/dL or above as high. Maintain an LDL cholesterol level under 100 mg/dL, realize that 100 to 129 mg/dL is considered near optimal/above optimal and think about LDL levels between 130 and 159 mg/dL as borderline high. If your LDL reading is 160 to 189 mg/dL, that's high and values above 190 mg/dL are very high. For optimal heart health, keep your HDL at 60 mg/dL or higher and view values below 40 mg/dL as unhealthy.
Recommendations
Since high blood serum cholesterol causes no symptoms, you won't know your values are abnormal unless you go into the laboratory for a cholesterol test. You should have a baseline blood serum cholesterol test done when you're 20 years old and repeat the test every five years, states the Mayo Clinic. Your doctor might order more frequent tests if your results are abnormal or you have a family history of high cholesterol or heart disease. Smoking, diabetes and high blood pressure increase your risk of coronary heart disease and may prompt your doctor to increase the frequency of your blood serum cholesterol tests.
Considerations
Illness, stress or a recent heart attack can cause your serum cholesterol level to be lower than normal. Wait at least six weeks after these events to get an accurate reading, says Lab Tests Online. Cholesterol levels vary normally over time, so your doctor may repeat any tests that show unhealthy levels.
References
- Medline Plus: Medical Dictionary: Serum
- American Heart Association: Good Versus Bad Cholesterol
- National Heart, Lung and Blood Institute: Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Executive Summary
- Mayo Clinic: High Cholesterol
- Lab Tests Online: Cholesterol: The Test
