Lipid levels similar regardless of whether patients fast before testing

Lipid levels did not vary significantly depending on whether patients fasted before lipid profile testing, according to a recent study.

Researchers used community-cohort laboratory data from Calgary, Canada, which included more than 200,000 people who had at least one lipid level tested and a fasting time recorded. Their mean total cholesterol level was 183.4 mg/dL, their high-density lipoprotein (HDL) level was 55.2 mg/dL, their low-density lipoprotein (LDL) level was 103.3 mg/dL and their triglyceride level was 127.6 mg/dL. Patients reported fasting times between 1 and 16 hours. Results were published by Archives of Internal Medicine on Nov. 12.

The study found that mean levels of total and HDL cholesterol didn't differ much according to fasting time. LDL cholesterol varied somewhat more, up to 10% across the range of fasting times. Mean triglycerides showed the greatest changes with fasting time, varying up to 20%. The study authors concluded that fasting times showed little association with lipid levels, indicating that routine recommendations for fasting may be unnecessary.

Fasting before testing causes a number of hassles, including inconvenience for patients, lower compliance with prescribed testing, and wait times at phlebotomy clinics, the authors noted. Based on this study and other recent research, they concluded that nonfasting testing is a reasonable alternative to fasting lipid testing, although patients who have a nonfasting triglyceride level of 400 mg/dL or higher should receive follow-up assessment.

An accompanying commentary agreed, although the author added high-risk patients such as diabetics to the list of those for whom nonfasting testing might not be appropriate. The commentary also pointed out several limitations to the study, including that most patients had fasted for at least nine hours, that the population was generally low-risk, and that the trial was not randomized. The authors of both the commentary and the study called for future research comparing fasting and nonfasting lipid levels in the same individuals.