To Fast or Not To Fast? That Is the Question

The days of fasting prior to a lipid test may be behind us, according to two-thirds of MedPage Today readers.

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    Cardiology Editor, MedPage Today

The days of fasting prior to a lipid test may be fading, according to two-thirds of MedPage Today readers.

A total of 63% of the more than 6,300 readers who voted in our survey indicated they would be fine if their patients ate before a cholesterol test.

The question was posed after a recent study found that lipid results were similar whether patients fasted or not. But the comments from readers suggested the topic will remain controversial, with one even putting a dramatic twist on the subject by referencing a popular 1950s television show.

"In comparing my patients' levels from test to test, the results are only relevant if the conditions are the same, and it is unlikely that a patient will exactly duplicate his/her timing and content of meals on draw days that are anywhere from 3 to 12 months apart," wrote a doctor of naturopathic medicine, who sided with the 25% of readers against nonfasting testing.

He also noted that blood draws are rarely only for lipid levels and may also include glucose parameters, which require fasting.

Of course, one study might not justify changing practice, as a few readers pointed out, but the population-based study that suggested fasting is unnecessary actually confirms many other smaller observational studies.

In addition, the population-based study involved more than 200,000 patients, which is "exceedingly powerful," commented Curtis Mark Rimmerman, MD, MBA, of the Heart and Vascular Institute at the Cleveland Clinic, to MedPage Today.

Rimmerman noted that nonfasting allows physicians to obtain cholesterol results while the patient is there, which can be discussed with the patient in the context of his/her food and exercise plan.

There were several readers who pointed out that the typical discussion of "cholesterol levels" seems to ignore triglycerides. Abnormal triglyceride levels can be "a red flag for pre-diabetes/insulin resistance."

It's more common today to assess high density lipoprotein cholesterol (HDL-C) and triglycerides along with low density lipoprotein cholesterol (LDL-C), readers said, hence the development of the lipid profile.

"Since the fed state has profound effects on triglyceride levels -- particularly in patients with disordered triglyceride transport, i.e, the frequently seen metabolic syndrome -- I strongly believe all lipid measurements should be drawn in the overnight fasted state," said one doctor.

And what if the patient is already on statins? "A nonfasting or only 4-hour fast would most likely reflect the actual lipid status," readers said.

Many readers noted that a nonfasting state is normal for more people, and the difference in cholesterol levels is generally minimal between fasting and nonfasting. But if the nonfasting test shows an atypical spike in some lipid levels, than a fasting retest would be in order, according to readers' comments.

Finally, there is the reader who invoked the two-faced character Eddie Haskell on the show "Leave It to Beaver" to explain the pros and cons of fasting and nonfasting.

Haskell was notorious for behaving one way around adults and another around his friends, uttering sentiments such as: "Wally, if your dumb brother tags along, I'm gonna...oh, good afternoon, Mrs. Cleaver. I was just telling Wallace how pleasant it would be for Theodore [the dumb brother] to accompany us to the movies."

The reader pointed out that "most people live more hours nonfasting than fasting. So the nonfasting state is more representative of what's going on in the patient's body throughout the course of a typical day, rather than a 6- to 8-hour intentional fast."

"Eddie Haskell's behavior around [parents] Mr. and Mrs. Cleaver is contrived and not representative of Eddie's real personality. That's the 'fasting level' for Eddie's behavior. The behavior he exhibits around Wally, Beaver, and his peers is more representative of his true behavior: that's the 'non-fasting level' for Eddie.

"So the question is if you were to evaluate Eddie Haskell and make behavioral recommendations for him, you would need to look at his behavior around Mr. and Mrs. Cleaver and his behavior around [his peers] in order to form a sound opinion and make sound recommendations. Because if you don't take both into consideration, then you are only seeing half the picture.

"Same thing applies to only using fasting blood levels: you're only using one factor to formulate an effective plan for the patient. You know very well a 6- to 8-hour fast is not representative of that patient's normal daily physiologic state," the reader concluded.

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