Health News Review

Lots of news coverage of an interesting study and accompanying commentary in this week’s “online first” edition of the Archives of Internal Medicine – suggesting that fasting may not be necessary before cholesterol tests.  From the banks of the Charles, Harold DeMonaco, MS, one of our expert story reviewers on HealthNewsReview.org, weighs in with his own lab analysis below.

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The study documents the effects of fasting on serum the serum lipid profiles of 209,180 patients who had blood drawn at a Calgary Canada laboratory.  I should point out that this was an observational study and has all of the liabilities as such.  However, the conclusions are of interest to those of us who have a hard time arriving to our physician’s office for a 3:00 pm appointment in the fasting state.  Here is there conclusion: “Fasting times showed little association with lipid subclass levels in a community-based population, which suggests that fasting for routine lipid levels is largely unnecessary.”

As has been pointed out on numerous occasions, a single study rarely provides the definitive answer to a medical question.  However, this study does shake up the time honored practice of only obtaining blood for laboratory studies in fasting patients, regardless of the testing.  While the study is interesting, the accompanying commentary clarifies the importance of the findings.  The commentary is a good reminder to journalists that accompanying editorials and commentaries provide additional insight into study conclusions and help put the results into perspective.

Boston.com’s The Daily Dose went a step further in its reporting and included comments by Dr. J. Michael Gaziano, the author of an accompanying editorial.  In his editorial, Graziano concludes, “Therefore, in practice, you can begin with a nonfasting lipid profile, and it is possible to use nonfasting levels for risk assessment, decisions about initiating treatment, and monitoring the effects of treatment. If you want to monitor triglyceride levels, then doing some sample fasting may useful. With this approach, most of our lipid profiles can be obtained in the nonfasting state, increasing convenience for our patients and ourselves and decreasing the burden on the laboratory, with no real adverse effect on clinical decision making.”

But I was much more interested in Dr. Gaziano’s comments in his interview with Deborah Kotz in the Globe’s Daily Dose.  Here’s the statement that got my attention, “Doctors can use the Framingham risk score calculation — based on total cholesterol, HDL, smoking status, blood pressure, and age — to calculate a person’s 10-year heart disease risk and determine whether cholesterol-lowering drugs or lifestyle modifications, such as increased exercise and a lower-fat diet, are warranted. “We don’t absolutely need an exact LDL measurement to make these decisions,” he said. 

Bravo to Ms. Kotz for not only providing a wonderful overview of the study and placing the results in context but also this wonderful quote from a thoughtful clinician. Contrary to what the pharmaceutical industry might have us believe, cardiovascular risk is indeed multivariate and not solely dependent on our lipid profiles, fasting or not.

Comments

Medbob posted on November 14, 2012 at 9:25 am

As a Lab Tech, the issue is not only Cholesterol. Triglycerides are important blood lipids that help the physician to get a full picture for diagnosis of lipid disorders.
Triglycerides not only vary widely based upon the patient’s fasting status, but can also interfere with other unrelated blood tests like cholesterol. The liquid portion of the blood (the part that is tested) can vary in color, based on triglyceride, from as clear as water, to as cloudy and opaque as milk. As many tests are performed by passing a beam of light through the sample mixed with other chemicals, it is obvious that Triglyceride can interfere.
The best testing that can be performed on a patient allows for both screening for disorder and also diagnosis of a disorder. By fasting, you insure that your Doctor gets the most accurate results possible on your “Lipid Panel”, and allows him to not only screen for high cholesterol, but also diagnose any problems you have in metabolizing fats. The above study ONLY looks at screening cholesterol. Being that High Triglyceride only affects a percentage of folks, it makes sense that the data would suggest that you don’t need to fast.
If you want to go to one of those Health Fairs and get cutesie numbers to take to your physician, go for it! It’s fun and can confirm your suspicion that you are in good health. If your physician sends you to a lab to have blood drawn, don’t forget to fast. It’s an important part of helping us get the most accurate picture of your health to relay to your physician.

Harold DeMonaco posted on November 14, 2012 at 12:30 pm

Thank you for your interesting comments. I think that you are missing the importance of Dr. Gaziano’s interview comments. A single laboratory value does not predict cardiovascular risk. At least that is what the Framingham Risk Score calculation would suggest. I would assume that a non-fasting sample would provide an elevated triglyceride providing perhaps false positive results. In fact the above paper does report on triglyceride levels. The one and twelve hour post prandial means differed by 26.3 mg/dl.

A published paper by Ridker in 2008 (http://www.clinchem.org/content/54/1/11.full ) supports the notion. that non-fasting lipid panels may be preferable in determining cardiovascular. Two previous papers (Nordestgaard BG, Benn M, Schnohr P, Tybjaerg-Hansen A. Nonfasting triglycerides and risk of myocardial infarction, ischemic heart disease, and death in men and women. JAMA. 2007;298(3):299-308 and Bansal S, Buring JE, Rifai N, Mora S, Sacks FM, Ridker PM. Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. JAMA. 2007;298(3):309-316) also support the concept.

JP posted on November 14, 2012 at 12:48 pm

Our host, Health News Review, has an express mandate to address the question of who is promoting a given position and to point out whether there is any underlying conflict of interest (COI). Toward that end, it should be noted that there is a considerable conflict of interest with Dr. Samia Mora, one of the authors of the invited commentary who wrote for the Archives of Internal medicine in support of the ‘convenience’ of lipid testing in the non-fasting state.

Dr. Mora’s COI was stated at the end of the original text in the invited commentary, but it appears to have been neglected by Health News Reviews and the news source cited above. Please see Archives of Internal Medicine, “Conflict of Interest Disclosures: Dr Mora has served as a consultant for Pfizer and Quest Diagnostics and has received speaking honorarium from Abbott, AstraZeneca, and the National Lipid Association for educational (nonpromotional) activities”.

In the invited commentary, Dr. Mora acknowledges: “Among nonfasting individuals, mean LDL-C levels were up to 10% lower, and triglycerides up to 20% higher, compared with fasting individuals”. Nonetheless, Dr. Mora concludes that: “These relatively small differences largely obviate the need for fasting”.

One expects that if pretest fasting is no longer a requirement of lipid testing, we will see a significant increase in public lipid-screening and a concomitant increase in the prescribing of lipid-lowering medication. To be clear, Dr. Mora consults for, and receives speaking fees from, pharmaceutical giants that are heavily invested in manufacturing, and promoting expanded usage of, lipid-lowering drugs. Time will tell if this serves corporate profit more than the public interest.