Cholesterol is a soft waxy substance your body uses to produce bile acids that digest your food, build and maintain healthy cells, create hormones and manufacture vitamin D. About 75 percent of the cholesterol in your body is manufactured in the liver and other body cells, while remaining 25 percent comes from animal foods in your diet. Although you need a certain amount of cholesterol to carry out these vital functions, abnormal serum cholesterol levels are unhealthy for your heart.
Identification
Serum is the watery part of your blood that's left after the blood cells are spun out in a laboratory. A serum cholesterol test measures the amount of specific types of cholesterol in that portion of your blood at a given point in time. For the most accurate results, avoid eating or drinking anything other than water for the nine to 12 hours before your blood test, advises MedlinePlus. Many drugs affect cholesterol readings, so consult your doctor to see if she wants you to stop taking these medications before your blood test.
Components
Since cholesterol is too fatty to dissolve in your blood, it hitches a ride on carriers known as lipoproteins. Low-density lipoprotein, or LDL, is known as the "bad" cholesterol, and high-density lipoprotein, or HDL, is the "good" type of cholesterol. The blood test will also measure your total serum cholesterol, which includes LDL, HDL, triglyceride fats and a genetic variant of LDL called Lp(a).
Roles
When your LDL and total cholesterol levels are too high, the excess cholesterol builds up on the inner lining of your arteries to form rigid plaques. HDL cholesterol, on the other hand, helps carry LDL to the liver so it can be excreted from your body. HDL may pull LDL cholesterol from the arterial plaques as well, notes the American Heart Association.
Expert Insight
The National Heart, Lung and Blood Institute publishes consensus guidelines for cholesterol management. Aim for a total serum cholesterol reading below 200mg/dL, realize that 200 to 239mg/dL is considered borderline high and view readings or 240 mg/dL and above as high. A cholesterol reading below 100mg/dL is optimal, near/above optimal is 100 to 129 mg/dL and 130 and 159mg/dL is considered borderline high. If your LDL is 160 to 189mg/dL, that's considered high and a reading of 190mg/dL or greater is very high. Since HDL is the beneficial form of cholesterol, shoot for results of 60mg/dL or greater and understand that values below 40g/dL are unhealthy.
Significance
Sit down with your physician to review and discuss the findings from your serum cholesterol test. Elevated LDL and total cholesterol coupled with low HDL readings increase your risk of developing coronary heart disease and suffering a heart attack or stroke. A heart-healthy diet and regular physical activity can help get your serum cholesterol levels back into the normal range.
References
- National Heart, Lung and Blood Institute: High Blood Cholesterol: What You Need to Know
- Medline Plus: Cholesterol Test
- American Heart Association: About Cholesterol
- 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
