No More Fasting For A Cholesterol Test?
Previously published on Answers.com.
For decades, a cholesterol test required fasting: 8-12 hours with absolutely no food or drink other than water. Not even gum or breath mints. This is a hassle, sure, but not too onerous as long as your appointment is first thing in the morning. If you can’t swing an early morning appointment, however, this can be terribly inconvenient (unless you are a teenager, in which case that’s no trouble at all – and gets you out of school).
Why is Fasting Important?
The reason fasting has traditionally been required for cholesterol testing is simple: lipid levels (and blood sugar levels) change hour-by-hour and depending on food consumption. It was believed that cholesterol levels could be elevated by as high as 20 points if the patient had not been fasting – and this could result in more aggressive treatment than necessary. Thus, fasting before cholesterol testing helped ensure that test results would not be skewed by a recent meal.
Is Water OK?
Water is not only permissible for a fasting blood test, it’s important. First it can help stave off the hunger pangs. But more importantly, it is difficult for the phlebotomist to draw blood from a patient who is dehydrated. So unless you don’t mind repeated arm pricks to find a vein, make sure you drink plenty of water before most any blood test – even a fasting blood test.
No More Need For Fasting?
But fasting may not be needed for accurate cholesterol testing, according to a study published in November 2012 in the Archives of Internal Medicine. In this large study of more than 200,000 people (half women) in Canada, average total cholesterol and HDL (good) cholesterol varied less than 2 percent among those who fasted and those who did not fast. For LDL (bad) cholesterol, the difference was less than 10 percent and for triglycerides it was less than 20 percent.
Dr. Christopher Naugler, an assistant professor of pathology at Calgary University and an author of the study, said, “It may even be that knowing a lipid level in a nonfasting state is a better way to estimate risk. No one knows yet.”
Should You Fast Before a Cholesterol Test?
It may be that you do not need to fast before a cholesterol test. Or it may be that your doctor is very concerned about an accurate triglyceride reading and still wants you to fast. Your best bet is to ask your doctor what is best for your personal situation.
Things change in the medical community. The common belief that fasting is necessary for cholesterol testing has been challenged by this Canada study, among others. While many doctors may still believe fasting before a cholesterol test is needed (and may be if a very accurate triglyceride level is important), this study questions that requirement. And that’s good, because a non-fasting test may encourage many more people to have their cholesterol tested on a regular basis.
Dr. Charles Naugler, an author of the study, said, “Eliminating fasting as a general requirement for cholesterol testing could greatly increase convenience for patients without significantly altering test results.“