November 13, 2012
No Fasting Needed Before Your Lipid Test
Brett Smith for redOrbit.com - Your Universe Online
Abstaining from food before your cholesterol test in the morning? Not so fast, say a pair of Canadian researchers.
According to two scientists from the University of Calgary, blood samples that were collected regardless of whether the test subjects had eaten recently or avoided food for more than the recommended eight hours showed similar average total cholesterol and "good" HDL cholesterol readings.
The results of the study, which was published in the Archives of Internal Medicine, could mean that facilities can take a different approach to performing and scheduling the tests.
"There are logistic challenges when you're going to get a fasting sample on everybody," said Dr. J. Michael Gaziano, who wrote a commentary that was published alongside the new study.
"It makes long lines and it makes long waiting times, and if that in any way discourages patients from having these tests done, then that's another downside,” he told Reuters.
Another problem typically associated with fasting before testing is that the test requires patients to return to the laboratory, and delays and further fasting could discourage those return visits.
In the study, the pair of researchers combed through the cholesterol test results for more than 200,000 people performed at the same lab over a six-month period in 2011. The doctors had also noted how long it had been since the patient had last eaten.
The researchers found that the mean cholesterol levels varied by less than 2 percent for total cholesterol and high density lipoprotein (HDL) cholesterol, regardless of fasting time. However, low-density lipoprotein (LDL), or ℠bad,´ cholesterol levels showed variations of up to 10 percent and the mean triglyceride levels showed variations of up to 20 percent.
The results mean that some patients who are taking specific medications to lower their cholesterol or triglycerides may need to fast before taking a cholesterol test, but other patients do not.
"For routine screening, we're suggesting that a 2 percent variance probably isn't going to be significant," study co-author Dr. Christopher Naugler, the chief of clinical pathology at the University of Calgary, told WebMD News.
The pair of researchers noted a few issues with their study, including the relatively low average age of the patients involved, 53, and low total cholesterol baseline, 183 mg/dL. These two factors might preclude the study results from applying to higher risk and older patients.
Another limitation of the study was that meal contents were not known before blood draws and a lack of observation could mean several of the self-reported fasting times were incorrect. The researcher also didn´t know who was or wasn't on any kinds of medication, including lipid-lowering drugs.
Despite these drawbacks, this latest study adds to a growing body of evidence that de-emphasizes the fasting period typically recommended before submitting to a cholesterol test.
"I think we've just taken for granted that we should do fasting for lipid testing," says Dr. Samia Mora, a preventive cardiologist at Brigham and Women's Hospital in Boston, who contributed to Gaziano´s commentary on the study.