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The next time you have blood drawn to check your cholesterol level, you may have a smile on your face.
The reason? You don't have to fast overnight and skip breakfast before your blood draw.
A new study provides further reassurance to patients and healthcare providers that you don’t have to fast overnight when having your blood drawn to check your cholesterol and other key indicators in your lipid profile.
The research, published in JAMA Internal Medicine, adds to existing studies which have found that nonfasting lipid levels are as accurate and clinically valid as fasting levels .
But the research goes one step further than previous guidelines and research supporting the validity of checking nonfasting lipid levels. It is the first study to look at the association of adverse outcomes--fatal heart attacks and coronary artery disease--in the same persons who had their lipids measured in the fasting vs. nonfasting state.
For the study, over 8,000 adults at increased risk for heart attack had fasting and nonfasting lipid levels measured 4 weeks apart. Data indicated that total, LDL, and HDL cholesterol levels demonstrated "negligible" differences between their fasting and nonfasting samples, while triglycerides were "modestly higher" in nonfasting samples.
The participants in the study were followed for about 3 years, in which 210 major coronary events (heart attacks) occurred. Nonfasting and fasting lipid levels demonstrated a similar association with heart attacks and development of fatal coronary artery disease. This finding was also noted in a more detailed evaluation of patients who had no history of coronary artery disease or heart attacks. In addition, nonfasting and fasting levels were equally accurate and correlated well in assigning patients into different levels of cardiac risk.
The researchers explain that their findings "provide robust evidence and more impetus for physicians to more broadly adopt nonfasting measurement of lipid levels for routine practice, in a manner consistent with ... recent guideline recommendations."
"This paper, and others who have recently reached the same conclusion, should be a relief to patients who had to configure their meals around having their blood drawn while fasting," offered Harlan Krumholz, M.D.,Professor of Medicine (Cardiology) at Yale University. " And so another thing we were so sure about in medicine, albeit a small but pesky one, hits the dust ."
But according to another expert, there still may be justification for ordering fasting lipid levels.
"The findings of the study are interesting--the fact that there is little difference between fasting and non-fasting blood cholesterol results would be reassuring to physicians and patients in a situation when patients are unable to fast, or patients forget to fast," said Guy L. Mintz, M.D., FACP, FACC, Director of Cardiovascular Health and Lipidology, Sandra Atlas Bass Heart Hospital, North Shore University Hospital, Associate Professor of Medicine, Zucker School of Medicine, Northwell Health. "The patients would not have to make a second appointment in a fasting state."
But "these findings would not change my clinical practice. When I order a patient blood panel I am also looking at blood sugar which should be done in a fasting state. Triglyceride levels, another part of the cholesterol panel are more accurate in the fasting state. Even in this study triglycerides were reported as ‘modestly higher' in the non-fasting state," he explained.
Mintz has other concerns about the details of the study itself: "I would also like to know what the patients in the non-fasting state ate prior to their blood tests. Did they have a light breakfast, full breakfast, high cholesterol breakfast, fruit, cereal or muffin? How many hours in advance of the blood test did they eat? What breakfast recommendations would we give patients when they are told to go for non-fasting bloods?"
"The study findings are reassuring and will be useful in clinical practice in certain situations." added Mintz.
Fasting to Check Your Lipid Profile-The Old Gestalt
Measurement of your lipid profile (cholesterol and triglycerides) has traditionally been recommended after an overnight fast primarily because of the concern that triglyceride levels would be significantly elevated affecting the accuracy of the measurement. However, this study and other well done studies demonstrate the there is only a minimal elevation of triglycerides, which does not vary significantly from the fasting state. In addition, clinical research demonstrates that the other elements of the lipid profile--total cholesterol, HDL, and LDL--do not result in any clinical significant changes compared with fasting results.
In addition, a number of risk estimators for primary prevention in patients not on lipid lowering medications do not include LDL, but rather total cholesterol and HDL, which are not significantly different between the fasting and nonfasting state. Other examples of clinical situations which do not require fasting include patients with elevated triglyceride levels, also known as hypertriglyceridemia, in which a single nonfasting level > 200 mg/dl serves as a threshold for intervention, with the plan for follow up fasting levels as a comparative. In situations when levels are significantly elevated (1000 mg/dl), treatment can begin without the need to repeat a fasting level.
One exception to drawing levels in a nonfasting state would include the screening and follow-up of people with a family history of genetic (familial) hyperlipidemia and premature atherosclerotic cardiovascular disease. In this case, an LDL > 190mg/dl is suggestive of familial hyperlipidemia and a fasting level is recommended.
