November 12th, 2012

Nonfasting Lipid Testing Gains Growing Acceptance

Although fasting before a lipid test has long been recommended, a new study and accompanying commentaries make the case that nonfasting lipid levels are acceptable and may even be superior to fasting levels for the assessment of cardiovascular risk.

Investigators at the University of Calgary analyzed data from laboratory tests obtained from more than 200,000 people and found that fasting time caused little variation in total cholesterol and HDL cholesterol levels, although LDL levels and triglycerides varied by as much as 10% and 20%, respectively. The finding, the authors write in their paper in the Archives of Internal Medicine, “suggests that fasting for routine lipid level determinations is largely unnecessary,” although patients with triglyceride levels over 400 mg/dL may require a fasting lipid level or a direct measurement of LDL.

In an accompanying editorial, J. Michael Gaziano writes that “the incremental gain in information of a fasting profile is exceedingly small for total and HDL cholesterol values and likely does not offset the logistic impositions placed on our patients, the laboratories, and our ability to provide timely counseling to our patients. This, in my opinion, tips the balance toward relying on nonfasting lipid profiles as the preferred practice.”

In an invited commentary, Amit Khera and Samia Mora take note of some limitations of the study but conclude that “given the current lack of evidence for the superiority of fasting lipid testing, it is reasonable to consider nonfasting lipid testing in most individuals who present for a routine clinic visit.”  Fasting levels may be indicated in people with high triglycerides and in high-risk patients such as diabetics.

14 Responses to “Nonfasting Lipid Testing Gains Growing Acceptance”

  1. Jean-Pierre Usdin, MD says:

    I do not agree with the fact that a variation of 10 or 20% in the dosage of triglycerides levels has no consequence.
    the “gold standard LDL level” depends of this result and a variation of 20% minus or more will definitely conduct to modify the treatment (and the classification in high or very high risk patient) this is not so harmless!)
    however for inpatients (patients) who need urgent check up (we have some people like this ) it may help but it will provoke cautious answers.

  2. Jeff Dickey, MD says:

    I have long used non-fasting lipid levels to screen for lipid profiles which may be associated with increased cardiac. Most people spend the vast majority of their lives in the non-fasting state. LDL may be slightly reduced post-prandially, but triglycerides may be higher, which may effect the sensitivity and specificity of the result relative to fasting. Non-fasting laboratory studies are a lot easier for patients and the number of non-compliant patients avoiding blood draws is anecdotally dramatically reduced. At least some evidence indicates that non-fasting lipids contribute to cardiac risk prediction. Non-fasting lipid results can be subsequently “confirmed” by fasting testing if that would influence management.

  3. David Powell , MD, FACC says:

    I agree. I will order non-fasting for logistic reasons. Postprandial or nonfasting triglycerides have complementary value with fasting assessments. I usually add a apo B in these circumstances, as I believe this does not vary. Furthermore, I tend to treat with evidence-based doses of statins, not particularly focusing on the LDL level, unless it is quite high. So I doubt a 10-20% LDL variation would significantly effect my choices. In fact, I’m not sure weather I even should be adding the apo B in most cases.

  4. I have been using non-fasting lipids for years as well as non-fasting glucose to screen for diabetes.

    Although still a weak marker for MI risk, non-fasting Non-HDL cholesterol is probably a more powerful marker than fasting LDL. In addition, non-fasting triglycerides have been shown to be more predictive of MI risk than fasting triglycerides in women.

    Non-fasting lipids are not only more convenient, they sacrifice no value and probably add value in risk prediction. That said, anyone who relies on such a weak marker as lipid measurements will miss the majority of subjects at MI risk and in addition will place too many subjects on statins who have no potential of benefit.

    I fail to see why we rely on poor predictors of risk when atherosclerosis imaging provides such a robust measure of MI risk as demonstrated in the MESA study.

  5. Jean-Pierre Usdin, MD says:

    OK All rihgt you win!!
    let’s change all the recommendations from ESC AHA ACC and put them in the bin!
    I agree: LDL below 70mg/dl for escondary prevention was a myth…

  6. Uffe Ravnskov, MD, PhD says:

    The question is, whether a lipid analysis is useful at all. May I remind of the results from the 30-year follow-up study from Framingham: “For each 1 mg/dl drop of cholesterol there was an 11 percent increase in coronary and total mortality”(1), and there is much more. More than 20 studies have shown that old people with high total or LDL cholesterol live the longest (2); at least 15 studies have shown that high cholesterol is not a risk factor for diabetics (3); low cholesterol is a risk factor for Russians (4), and recently two studies found that total and/or LDL cholesterol on average was lower than normal in patients with an acute myocardial infarction (5,6). In one of these studies the patients were followed for 3 years. At follow-up mortality was highest among those who had the lowest cholesterol (6). Add also that high cholesterol is not a risk factor for women (7). There is obviously something wrong with the cholesterol hypothesis

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  7. Jean-Pierre Usdin, MD says:

    we wake up a supporter of “all cholesterol are safe for your health”
    finally no need to check the cholesterol and triglycerides whatever fasting or nonfasting…

  8. Neville Wilson, M.B., Ch.B., D.Fam. Med., M.Sc., D.Obs (COG) SA., B.A. says:

    Several years ago I conducted a personal experiment to assess the effects of a prior cholesterol rich meal on my serum lipid parameters. I consumed 8 eggs each morning for 8 days followed by phlebotomy 1-2 hours later,
    by my practice nurse, and lipid analysis at my regular laboratory.
    I conducted the experiment in the belief that dietary cholesterol has a minimal role to play in serum cholesterol levels, and that conventional recommendations to reduce dietary cholesterol and saturated fat as a risk reduction strategy in CAD prevention was neither good science, nor evidence based. Over the following 10 days my lipid levels remained largely unchanged, with a slight elevation of Triglyceride after a week.
    I do not subscribe to the conventional practice of testing fasting lipids, and am perturbed by the traditional practice of instructing patients to go on a “low cholesterol diet” and to return for a “fasting cholesterol test “.
    Apart from the logistical challenge for patients to comply with this recommendation, there is the added burden of unwarranted anxiety induced by such an instruction, and an added danger of dehydration associated with a fast, which may yield an artificially elevated lipid level, resulting in unnecessary pharmacological intervention.
    Data from the Emerging Risk Factors Collaboration way back in 2009 support the contention that fasting is not necessary for lipid assessment and quantifying cardiovascular risk. (JAMA vol. 302 No.18, Nov 11, 2009)

  9. Bruce Wells, MD says:

    Why not switch to using non-HDL cholesterol values exclusively, thus avoiding the fasting/nonfasting debate. Haven’t these been shown to be as accurate as fasting LDL levels?

  10. Björn Hammarskjöld, M.D., Ph.D. says:

    An egg contains about 200 mg cholesterol and your blood has between 8 000 to 16 000 mg (=56 times more cholesterol in a 70 kg person with 5.6 L blood than the mg/dL value indicates).
    The total amount of cholesterol in the body is more than 35 000 mg. So how much does an egg’s 200 mg change the total amount of cholesterol in the body? Less than 0,5 percent. The variation of total blood cholesterol between two samples taken minutes apart can vary more than 5 %.
    Why worry about ingested cholesterol?

    In Läkartidningen (Swedish equivalent of JAMA) states that more than 90 % of the population above 65 years of age have a total cholesterol of more than 5 mmol/L or 200 mg/dL. This means that those with lower cholesterol values have died off before the age of 65. Also, patients with a low cholesterol value and AMI suffer a higher rate of death than those with a higer total cholesterol value.

    Next question:
    Why worry about high cholesterol at all?

  11. the only worry i had was strict levels of HDL >40 & >50 mg/dl, in males and females, resp. apart from various LDL levels depending upon various risk factors.

    but having gone thru this discussion & with my recent studies, i conclude
    1. Non HDL levels are more important.
    2. fasting is not important.
    3. the ratio’s could be the next big thing, no pressing upon strict goals – balance is important.

  12. Neville Wilson, M.B., Ch.B., D.Fam. Med., M.Sc., D.Obs (COG) SA., B.A. says:

    Thanks for that, Bjorn. I totally agree. The recently reported (Atherosclerosis)study by 3 Canadian researchers that eggs are almost as bad for health as is cigarette smoking,is a very questionable attempt to damage the reputation of healthy egg yolks, and hopefully readers will not have missed the flawed methodology underlying their misleading hypothesis !

  13. Joel Wolkowicz, MDCM says:

    Why do we worry about the accuracy of triglyceride measurements? Will a modest (or larger) inaccuracy affect management and outcome?