Fasting for at least 8 hours before lipid level measurement is recommended to decrease variability and improve consistency at the time of the test. However, new data published in the Archives of Internal Medicine suggest that fasting for routine lipid levels is unnecessary.
“The results presented herein, combined with those of other recent studies, suggest that nonfasting determination of lipid subclasses is a reasonable alternative to fasting determinations,” the researchers wrote. “In individuals with an initial triglyceride level higher than 400 mg/dL, follow-up assessment of fasting lipid levels and/or direct measurement of LDL cholesterol levels should be considered.”
Davinder Sidhu, MD, LLB, and Christopher Naugler, MSc, MD, CCFP, FCFP, FRCPC, of the department of pathology and laboratory medicine at the University of Calgary in Alberta, Canada, conducted a cross-sectional analysis of a community-based cohort during a 6-month period at Calgary Laboratory Services in 2011.
The fasting time was split into hourly intervals from 1 to 16, and fasting times of more than 16 hours were included in the 16-hour group. Additionally, patients who fasted less than 1 hour were included in the 1-hour group. The patients were analyzed according to sex in linear regression models, researchers wrote.
Of 209,180 patients (111,048 females) included in the study, the mean cholesterol subclass levels varied by less than 2% for total cholesterol and HDL cholesterol, less than 10% for calculated LDL cholesterol, and less than 20% for triglycerides, Sidhu and Naugler wrote.
In an accompanying editorial, J. Michael Gaziano, MD, MPH, of the department of medicine at VA Boston Healthcare System, Brigham and Women’s Hospital, and Harvard Medical School, wrote that optional fasting could provide a convenience to patients and practitioners without adverse effects on clinical decision making.
“While there are some circumstances in which a fasting level may be useful, most of the time it is probably not necessary,” Gaziano wrote.
Additional commentary by Amit V. Khera, MD, and Samia Mora, MD, MHS, of the divisions of internal medicine, preventive medicine and cardiovascular disease at Brigham and Women’s Hospital and Harvard Medical School, support Sidhu and Naugler’s suggestion due to small differences unlikely to affect cardiovascular risk scores.
“However, given the current lack of evidence for the superiority of fasting lipid testing, it is reasonable to consider nonfasting lipid testing in most individuals who present for a routine clinic visit, with the possible exceptions of individuals with triglyceride levels greater than 400 mg/dL,” they wrote.
They recommend further studies before a nonfasting lipid testing strategy is enforced.
For more information:
Gaziano JM. Arch Intern Med. 2012;doi:10.1001/jamainternmed.2013.1771.
Khera AV. Arch Intern Med. 2012;doi:10.1001/2013.jamainternmed.263.
Sidhu D. Arch Intern Med. 2012;doi:10.1001/archinternmed.2012.3708.
Disclosure: 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 (non-promotional) activities. All other researchers report no relevant financial disclosures.