Fast Before Cholesterol Test? Study Says No
< Nov. 14, 2012 > -- The next time you need a routine blood test to check your cholesterol, you may not need to fast beforehand.
Although the standard routine for checking cholesterol requires people to fast nine to 12 hours before having their blood drawn, a new study adds to growing evidence that fasting isn't necessary.
Researchers at the University of Calgary, in Canada, looked at lab data on cholesterol tests for more than 200,000 people. They compared fasting time with the cholesterol results. The results were published online this week in the Archives of Internal Medicine.
Overall, they found that fasting time made little difference in the accuracy of the blood test:
Levels of HDL ("good") cholesterol varied less than 2 percent with different fasting times.
LDL ("bad") cholesterol levels differed up to 10 percent.
Triglyceride levels differed up to 20 percent.
"For routine screening, fasting for cholesterol is largely unnecessary," says lead researcher Christopher Naugler, M.D. And not requiring fasting could make it more convenient for people to get their cholesterol screened, he says.
Samia Mora, M.D., at Brigham and Women's Hospital in Boston agrees.
"It's easier for patients, as it usually saves them from coming a second time after fasting," says Dr. Mora, who co-wrote an accompanying journal commentary. "It's easier for physicians as well, as they can have the results faster. And it may potentially save costs, as sometimes individuals may have to repeat a blood test just for lipids if they weren't fasting the first time."
A nonfasting blood test may also be a better predictor of a heart attack or other cardiovascular problem, according to Gregg Fonarow, M.D., at the University of Los Angeles-California.
Some people may need a fasting cholesterol test, however. Those with abnormally high triglycerides may need repeated fasting tests to get an accurate measurement, Dr. Naugler says.
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Know Your Cholesterol Levels
You can't tell whether you have high blood cholesterol by how you feel - the condition has no symptoms in itself. That's why it's important to find out what your cholesterol level is.
Keeping your cholesterol within healthy limits is important for you no matter what your age or gender. That's because having high cholesterol makes it more likely that you will develop cardiovascular disease.
Everyone age 20 or older should have a blood cholesterol test at least once every five years. The most accurate test is the "lipoprotein profile."
A lipoprotein profile measures:
LDL ("bad") cholesterol, which is the main source of cholesterol buildup and blockage in the arteries
HDL ("good") cholesterol, which helps keep LDL cholesterol from building up in the arteries
Triglycerides, which are another form of fat in your blood
VLDL (very low-density lipoproteins) and a cholesterol/HDL ratio may also be included in the profile.
Always talk with your health care provider to find out more information.
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American Heart Association - Cholesterol
Archives of Internal Medicine - Fasting Time and Lipid Levels in a Community-Based Population
National Heart, Lung, and Blood Institute - High Blood Cholesterol: What You Need to Know