Cholesterol test fasting 'largely unnecessary'
Non-fasting tests more convenient for patients
Posted: Nov 13, 2012 12:08 PM ET
Last Updated: Nov 13, 2012 2:05 PM ET
Fasting before getting a blood test of cholesterol levels may be unnecessary, a new Canadian study suggests.
Current guidelines suggest taking blood samples for lipid tests like high-density lipoprotein or HDL cholesterol after fasting for nine to 12 hours, but the requirement isn't always practical for patients.
Fasting for routine blood work may discourage patients from going for the tests and blood labs may have long wait times in the morning that inconvenience people even more.Fasting for routine blood work may discourage patients from going for the tests. (Jose Leiva/Sun Journal/Associated Press)
In Monday's issue of the Archives of Internal Medicine, Dr. Davinder Sidhu and Dr. Christopher Naugler of the University of Calgary looked at how long 209,180 people in Calgary fasted and their lipid results. Last year, the city's laboratory service changed its policy allowing samples to be processed regardless of the fasting time.
"We found that fasting time showed little association with lipid subclass levels in a large community-based cohort," the study's authors concluded. "This finding suggests that fasting for routine lipid level determinations is largely unnecessary."
HDL and total cholesterol levels varied less than two per cent with different hours of fasting while triglyceride levels varied by about 20 per cent, the researchers found.
"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, many of whom have difficulty with prolonged fasting."
The study's authors pointed out they weren't able to consider meal choices before the blood draws. They also weren't able to control for errors in the self-reported fasting times or the medications that patients were taking.
Proponents of fasting for lipid testing say fasting was used in most studies on predicting cardiovascular risk and in most clinical trials of statins, Dr. Samia Moria of the medicine department at Brigham and Women's Hospital in Boston said in a journal commentary accompanying the study.
The length of fasting wasn't randomly assigned in the study, which included participants who were relatively young with an average age of 53. Moria cautioned the results may not apply to patients at higher risk, such as those with diabetes.
The usefulness of fasting for the tests in terms of greater precision in some measurements needs to be weighed against the challenges and perhaps missed opportunities imposed by requiring fasting and a morning trip to the lab, Moria said.
Moria called for more studies to validate the nonfasting approach before it's universally endorsed, adding it's reasonable to consider in most people coming for a routine clinical visit.
A journal editorial by Dr. Michael Gaziano of the aging division and Brigham and Women's and Harvard suggested that doctors start with a nonfasting lipid profile to assess a patients' risk, decide about starting treatment and then monitor the effects of treatment. But some fasting may be useful to monitor triglyceride levels.
"With this approach, most of our lipid profiles can be obtained in the nonfasting state, increasing convenience for our patients and ourselves and decreasing the burden on the laboratory, with no real adverse effect on clinic decision making," Gaziano concluded.
Gaziano and the study's authors said they had no conflicts of interest. Moria has consulted to Pfizer and Quest Diagnostics and received speaking fees from Abbott, AstraZeneca and the National Lipid Association for educational activities.
Top News Headlines
- Will alleged Rob Ford video overshadow Toronto casino debate?
- A debate about a proposed downtown casino is supposed to take centre stage at Toronto City Hall on Tuesday, but it seems a safe bet that a still-unseen video of Mayor Rob Ford will continue to be a topic of conversation. more »
- Harper to address Tory caucus amid Senate scandal
- Conservatives gathered Monday night to mourn the passing of a key architect in their rise to power — and to brace for the toughest test Prime Minister Stephen Harper's government has faced since taking office on a promise to clean up politics in the national capital. more »
- Keith Boag: Have you heard about the murderous abortion doctor?
- The gruesome trial and murder conviction of Philadelphia abortion provider Dr. Kermit Gosnell is unlikely to change American abortion law, Keith Boag writes. But it has U.S. journalists questioning their priorities and how they cover such a sensitive issue. more »
- Fearful Oklahoma families search for children
- The parents and guardians stood in the muddy grass outside a suburban Oklahoma City church, listening intently as someone with a bullhorn called out the names of children who were being dropped off — survivors of Monday's deadly tornado. more »
Latest Health News Headlines
- Sleeping with parents always risky for infants, study suggests
- Sharing a bed with their parents increased the risk of sudden infant death syndrome (SIDS) in babies under three months old by at least a factor of five, even without any other risk factors, the largest ever analysis of individual cases suggests. more »
- Flu shot for health workers urged by Ont. medical officer
- Ontario's chief medical officer of health is renewing her push for health-care workers, particularly those in long-term care, to get their shots. more »
- Saudi coronavirus work stymied at Canadian lab
- The National Microbiology Laboratory in Winnipeg is working with a sample of the new coronavirus that's causing clusters of infections abroad - but can't share the material with other researchers across the country despite the public health urgency. more »
- Should genetic testing for cancer be available to all Canadians?
- The revelation that Hollywood celebrity Angelina Jolie had a double mastectomy as a preventative measure against cancer stoked heated discussion this past week, but one prominent cancer researcher says it demonstrates the need to make genetic testing available to all Canadians. more »
- 51 dead after tornado levels Oklahoma suburbs
- Oklahoma tornado rescue crews work through night
- Edmonton driver, 62, charged in boy's patio death
- Unknown remains found on Dellen Millard's farm
- Will alleged Rob Ford video overshadow Toronto casino debate?
- Netflix and the rise of binge TV watching
- Ray Manzarek of The Doors dies at 74
- B.C. man feared kidnapped in Mexico
- Canadian on EI shut out amid foreign worker influx