Your doctor may ask you to fast before an upcoming cholesterol test, and for good reason. Cholesterol tests that give a complete and accurate picture require a preceding fast. And obtaining an accurate picture of your cholesterol profile is important since high cholesterol is a risk factor for heart disease, the number one killer of men and women in America, according to 2006 statistics provided by the American Heart Association.
Why Cholesterol Matters
Cholesterol is a waxy substance naturally found in cells and required for normal body function. You also obtain cholesterol from animal products you consume such as red meat and dairy products. Cholesterol circulates throughout the blood and in excess, over time, it can narrow, harden and clog your arteries. When this happens, tissues and organs, such as the heart, don't receive optimal blood circulation, and heart disease or heart attack can occur.
Types of Cholesterol Measured
Cholesterol testing gives the value for total cholesterol, triglycerides, LDL cholesterol and HDL cholesterol. Triglycerides are a type of fat in the blood that often correlate with high cholesterol; elevated triglyceride levels are another risk factor for heart disease. Low-density lipoprotein cholesterol, or LDL, is considered unhealthy because it is delivered to tissues throughout the body and can deposit in the arteries, leading to plaque buildup. Alternatively, high-density lipoprotein, or HDL, cholesterol is considered good because it helps remove cholesterol from tissues. For good health, values for total cholesterol should be below 200 mg/dL, below 150 mg/dL for triglycerides, below 100 mg/dL for LDL and above 60 mg/dL for HDL.
Lipid Profile Testing
When your doctor recommends a complete lipid profile, a fast 9 to 12 hours before the blood test is required. No food, beverages or medications are allowed during this time. Because the food you recently consumed affects your triglyceride and LDL cholesterol levels, the fast is necessary to get a complete profile with accurate values for total cholesterol, HDL, LDL and triglycerides levels. A cholesterol test without a preceding fast, called a screening cholesterol test, only provides accurate values for total cholesterol and HDL.
Recommendations
Healthy adults with no history or risk factors for heart disease should get a complete lipid profile every 5 years, notes the American Association for Clinical Chemistry. You should first get a lipid profile test at age 20. If a cholesterol screening test indicates borderline or high levels, your doctor may follow-up with a lipid profile. Children and teenagers don't require a lipid profile unless they are at increased risk for developing heart disease in the future.
References
- American Heart Association; Women and Cardiovascular Disease Statistics - 2010
- National Institutes of Health; Lowering Cholesterol with TLC; Dec. 2005
- American Heart Association; How to Get Your Cholesterol Tested; Jan. 20, 2011
- American Association for Clinical Chemistry; Lipid Profile; March 22, 2011
