Fasting for routine lipid testing may be unnecessary. A large community-based study published in the Archives of Internal Medicine on Dec. 10 contributes to a growing body of literature demonstrating minimal differences between fasting and nonfasting mean cholesterol levels, leading many experts to say that nonfasting blood draws may be used for cardiovascular risk assessment and therapeutic decisionmaking. Laboratory data from 209,180 individuals (111,048 females and 98,132 males) seen by Calgary Laboratory Services over a six-month period were analyzed. A 2011 policy change permitted the laboratory to process patient samples for fasting lipid levels regardless of the duration of the fasting time as long as the patient-reported fasting time (in hours) was recorded. High-density lipoprotein (HDL) cholesterol and triglyceride levels were measured directly, while low-density lipoprotein (LDL) cholesterol levels were estimated. For total cholesterol and HDL cholesterol mean levels varied by less than 2 percent across various fasting times. Triglyceride levels varied by less than 20 percent and the calculated LDL cholesterol varied by less than 10 percent. “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 […]
Fasting for routine lipid testing may be unnecessary. A large community-based study published in the Archives of Internal Medicine on Dec. 10 contributes to a growing body of literature demonstrating minimal differences between fasting and nonfasting mean cholesterol levels, leading many experts to say that nonfasting blood draws may be used for cardiovascular risk assessment and therapeutic decisionmaking.
Laboratory data from 209,180 individuals (111,048 females and 98,132 males) seen by Calgary Laboratory Services over a six-month period were analyzed. A 2011 policy change permitted the laboratory to process patient samples for fasting lipid levels regardless of the duration of the fasting time as long as the patient-reported fasting time (in hours) was recorded. High-density lipoprotein (HDL) cholesterol and triglyceride levels were measured directly, while low-density lipoprotein (LDL) cholesterol levels were estimated. For total cholesterol and HDL cholesterol mean levels varied by less than 2 percent across various fasting times. Triglyceride levels varied by less than 20 percent and the calculated LDL cholesterol varied by less than 10 percent.
“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,” writes J. Michael Gaziano, M.D., from Brigham and Women’s Hospital in Boston, in an accompanying editorial. “This, in my opinion, tips the balance toward relying on nonfasting lipid profiles as the preferred practice.”
While current guidelines still recommend that blood for lipid profiles should be drawn after a nine- to 12-hour fast, other recent studies suggest that nonfasting lipid profiles may be superior to fasting levels in predicting adverse cardiovascular outcomes as nonfasting values may be more representative of usual metabolic conditions and lipid clearance. While clinicians still believe fasting lipid tests are necessary in individuals with triglyceride levels greater than 400 mg/dL and in other high-risk patients, the growing consensus is that removing the fasting requirement will improve clinical care and testing compliance.
“The elimination of a fasting requirement for lipid determination could also increase patient compliance with testing, which could have particular benefits for patients with diabetes,” writes study co-author Davinder Sidhu, M.D., from the University of Calgary in Canada. “These findings suggest that analysis of fasting time and lipid levels could have a role in identifying individuals for further screening with supplementary tests such as oral triglyceride tolerance testing or more rigorous treatment protocol goals and closer monitoring.”
