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Fasting might not be necessary before cholesterol test


Fasting before blood lipid tests appears to have limited association with lipid subclass levels, suggesting that fasting for routine lipid level determinations may be unnecessary, according to a study.

“Although current guidelines recommend measuring lipid levels in a fasting state, recent studies suggest that nonfasting lipid profiles change minimally in response to food intake and may be superior to fasting levels in predicting adverse cardiovascular outcomes,” wrote Davinder Sidhu, MD, LLB, and Christopher Naugler, MD, CCFP, FCFP, FRCPC, with the University of Calgary, in background information for the study.

The authors conducted a cross-sectional examination of laboratory data, which included fasting duration and lipid results, over a six-month period in 2011. A total of 209,180 participants (111,048 women) were included in the analysis.

In general, the authors found the average levels of total cholesterol and high-density lipoprotein differed little among individuals with various fasting times. Specifically, levels varied by less than 2% for total cholesterol and HDL cholesterol, by less than 10% for calculated low-density lipoprotein cholesterol and by less than 20% for triglycerides.

“We found that fasting time showed little association with lipid subclass levels in a large community-based cohort,” the authors concluded. “This finding suggests that fasting for routing lipid-level determinations is largely unnecessary.”

In an accompanying editorial, J. Michael Gaziano, MD, MPH, of Brigham and Women’s Hospital, Harvard Medical School and VA Boston Healthcare System, wrote: “Most of the reasons that we measure a lipid profile depend on total and HDL cholesterol levels for most of our decision making. 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 a separate commentary, however, Amit V. Khera, MD, and Samia Mora, MD, MHS, also of Brigham and Women’s Hospital and Harvard Medical School, wrote: “Additional prospective studies that directly compare the association of fasting and nonfasting lipid levels with cardiovascular outcomes in the same individuals would be informative. Further validation studies are needed before a nonfasting lipid testing strategy is universally endorsed.”

The study appeared Nov. 12 on the website of the Archives of Internal Medicine and is available at


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