Forget Fasting Before This Blood Test
An empty stomach isn't needed for accurate cholesterol numbers
Need to get your cholesterol levels checked?
“You don’t have to fast ever again,” Dr. Borge Nordestgaard, a researcher from the University of Copenhagen in Denmark, told LifeZette.
His latest report in the European Heart Journal explains that people do not need to have cholesterol testing done on an empty stomach. Currently, it’s normal to fast before cholesterol and triglyceride testing in all countries except Denmark. There, doctors have been using non-fasting blood sampling since 2009.
“I see no advantage for any patient at all for using fasting lipid testing. None,” he told LifeZette. “Non-fasting values are plenty accurate for what you want to know, and for triglycerides, non-fasting values may even better tell what the person’s risk of cardiovascular disease is.”
The report involved looking at data from older studies of more than 300,000 people from the U.S., Canada, and Denmark. It showed that cholesterol and triglyceride levels are similar whether people fast or not.
This doesn't mean you can pig out before your blood test, however. Dr. Michael Miller, a professor at the University of Maryland School of Medicine and author of "Heal Your Heart," agreed with the new report and cited his own 2011 research for the American Heart Association on triglycerides and cardiovascular disease. He found it was OK not to fast as long as the person ate less than 15 grams of fat.
As long as you restrict your fat intake on the day you have blood drawn, you're fine, Miller said.
"This relatively low intake does not measurably affect cholesterol or triglyceride levels," Miller told LifeZette. If you consume more than 15 grams of fat, however, it could make the test less accurate.
Miller said the concept was introduced to doctors in 2011 with "some movement," so he expects the Denmark study will help doctors in the U.S. to move toward non-fasting tests.
Dr. Regina Druz, a cardiologist in New York, doesn't think doctors should use a one-size-fits-all approach. If she is evaluating a patient with advanced lipid testing such as particle measurements, inflammatory markers, and levels of triglycerides and glucose, for example, she advises the person fast for four to six hours to eliminate any possible effect of food on triglycerides and fasting blood sugar. If it's a patient who does not have previous cholesterol issues, however, she doesn't require the patient to fast and decides on additional testing after seeing results.
"The cholesterol measurements are unlikely to be affected to a degree that changes clinical decision-making in the screening tests, regardless if a patient is fasting or not," said Druz. But if decisions need to be made about treatment, such as use of statin drugs, a more detailed and rigorous testing is advantageous and that includes an eight-hour fast.
"In all of these situations, convenience and cost have to be balanced against accuracy and clinical decision-making," Druz noted.
Dr. Dennis Goodman, a professor at NYU who specializes in cholesterol management, said he likes to see people with triglyceride issues fast and have their tests done at the same time of day. But he said that anyone else looking to know general cholesterol numbers does not need to fast.
"Besides triglycerides, everything else [testing other cholesterol levels without fasting] doesn't matter," he said.
"I think this will become mainstream in the U.S., because it simplifies clinical practice for patients, doctors, and laboratories," Nordestgaard said.
Dr. Kevin Campbell, a cardiologist in North Carolina, said that this isn't the first study to suggest not fasting. He noted that guidelines on lipid management from the American College of Cardiology still recommend fasting before lipid panels. Campbell believes the ACC will change its recommendation the next time it revises the guidelines.
"As more studies, such as the latest study from Denmark, are released, we will be more likely to adopt a non-fasting strategy in the U.S.," he told LifeZette.