Use Nonfasting Blood for Routine Lipid Profiles, Says EAS/EFLM

Marlene Busko

May 04, 2016

COPENHAGEN, DENMARK — The European Atherosclerosis Society (EAS) and the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recommend that "nonfasting blood samples be routinely used for the assessment of plasma lipid profiles" (total, LDL, and HDL cholesterol and triglycerides) in a joint statement that was published online April 26, 2016 in the European Heart Journal[1].

The international writing committee of experts from eight European countries, Australia, and the US add the caveats that clinicians should consider repeating a nonfasting lipid profile test with a fasting test if plasma triglycerides are above 5 mmol/L (440 mg/dL), and importantly, they should immediately refer a patient with life-threatening or extremely high concentrations of triglycerides or LDL cholesterol to a lipid clinic or a physician who specializes in lipid disorders.

Moreover, laboratory reports should flag abnormally high nonfasting lipid values.

"I hope that most laboratories in the entire world will stop asking patients to fast before lipid profile testing, as this might make more people have cholesterol and triglyceride measurements [and] ultimately, together with their doctor, facilitate focus on prevention of cardiovascular disease," lead author Dr Børge G Nordestgaard (Copenhagen University Hospital, Denmark) told heartwire from Medscape in an email. "People with objections should read our consensus statement," he said.

In 2009, the Danish Society for Clinical Biochemistry recommended that routine lipid profiles be measured in nonfasting blood samples with the option of doing a repeat test if triglycerides were above 4 mmol/L (350 mg/dL), and this has been standard clinical practice in Denmark since then. Similarly, in 2014 UK NICE guidelines recommended this practice.

In contrast, the 2013 American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Practice Guidelines[2] recommended that a fasting blood sample is "preferred" for lipid testing, although a nonfasting blood sample could be used.

But are the recommendations really so far apart? Invited to comment, Dr Neil J Stone (Feinberg School of Medicine, Northwestern University, Chicago, IL), chair of the 2013 American College of Cardiology (ACC)/American Heart Association (AHA) Task Force on Practice Guidelines, told heartwire that according to the guideline risk estimator, "clinicians most of the time can use nonfasting lipids if their question is, 'What is the risk of heart attack and stroke for this patient?'

"I would argue that all of us are saying very close to the same thing. It really does depend on the question you're asking," he said.

New Clinical Evidence

The consensus statement aimed to evaluate the clinical implications of using nonfasting vs fasting blood samples for lipid profiles to guide clinicians and laboratories.

The advantages of a determining lipid profiles in a nonfasting blood sample are that patients who have not fasted do not have to make another appointment to have their blood drawn, the statement authors note. By not requiring an overnight fast, the crowd of patients showing up in the morning for a blood test is lessened, and physicians are spared from having to track down repeat tests.

On the other hand, fasting samples have been used in many clinical trials that inform guidelines. And the increase in triglycerides that occurs after eating a fatty meal has been thought to greatly affect the calculation of LDL cholesterol using the Friedewald equation.

New evidence from more than 300,000 patients in studies from Canada, the US, and Denmark has shown that that the change in lipids and lipoproteins in response to people's habitual meals is not clinically significant, Nordestgaard said. Moreover, other new data show calculated or directly measured LDL cholesterol is similar whether a person fasts or not.

In addition, "experience from Denmark since 2009 shows that in more than 5000 hospital patients, triglyceride levels measured in the same individuals at two different occasions (fasting and nonfasting) gave similar results, even at very high triglycerides and in those with diabetes," he noted.

Nevertheless, "while the mean average numbers for fasting and nonfasting LDL cholesterol, for example, were only 8 mg/dL apart, those are means," and this difference can be much greater in some individuals, Stone pointed out. A nonfasting sample could be used if the patient has just eaten a meal with less than 15 g of fat, he said. "I think there's going to be a gradual trend to see more and more nonfasting [lipid tests], but it's going to require education of our patients to not come in after a very high-fat meal the day of testing," he said.

Practical Implications

The consensus statement authors summarize that "a nonfasting sample can routinely be used to assess plasma lipid profiles in most situations," including an initial lipid profile test in any patient; for a cardiovascular risk assessment; for a patient admitted with acute coronary syndrome; in children; in patients who prefer this; in diabetic patients (due to hypoglycemic risk); in the elderly; and in patients on stable drug therapy.

However, "fasting can sometimes be required," they add, for example, if a patient has nonfasting triglycerides >5 mmol/L (440 mg/dL) or known hypertriglyceridemia (and is being followed in lipid clinic),  is recovering from hypertriglyceridemic pancreatitis or is starting medications that cause severe hypertriglyceridemia or if additional laboratory tests are requested that require fasting or morning samples (eg, fasting glucose or therapeutic drug monitoring).

The study was supported by unrestricted educational grants to EAS and EFLM from Merck, Roche Diagnostics, and Denka Seiken. These companies had no role in the design or content of the joint consensus statement and had no right to approve or disapprove of the final document. Funding to pay the open-access publication charges for this article was provided by the EAS and the EFLM. Nordestgaard and Stone have no relevant financial relationships; disclosures for the coauthors are listed in the article.

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