By: Nagma Gargi, Pharm D. Candidate 2013
Traditionally, lipid panels are drawn under fasting conditions. Is there data supporting decreased accuracy in a non-fasting lipid panel?
Cholesterol is an essential tool for our body for the synthesis of hormones, vitamin D, and bile acids. However, an excess of cholesterol pose a serious threat to our health as it contributes to heart disease, stroke, and other comorbidities. Knowing our cholesterol level is fundamental in helping us identify when and how to take proper measures (i.e. therapeutic lifestyle changes) towards keeping our cholesterol levels within normal ranges. To take precautions and preventative measures at the right time, most doctors mandate a lipid panel at least once every year for males ≥ 35 years of age, and for females ≥ 45 years of age. A lipid panel is a blood test that measures the following lipids—cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL).
To obtain an accurate lipid panel, the patient is asked not to eat any food and drink any beverages (other than water) from nine to twelve hours before the panel. Food may not actually affect the levels of total cholesterol and HDL cholesterol. However, according to the Harvard Medical Center, it can cause your triglyceride levels to rise upward by 20-30 percent, which inevitably produces an incorrect reading. It’s also important to stay away from all alcoholic beverages for at least twenty-four hours before your cholesterol test for the same reasons (“Harvard Health Letter” 4-5). Prescription, OTC medications, and herbal supplements can also sway the readings yielded by a standard cholesterol test. Before scheduling your lipid profile, it’s recommended you discuss your current medication list with your doctor or pharmacist.
Although a fasting lipid panel is a traditional requirement, the big question today is the extent to which fasting lipid levels are more accurate than nonfasting lipid levels. A cross-sectional study was conducted to test out this very hypothesis using 33,391 participants from the Copenhagen General Population Study as well 9,319 individuals from the Copenhagen City Heart Study. Via the use of efficient methods, procedures and a fourteen-year follow-up, individuals in the general population had a maximum mean change from fasting levels of −0.2 mmol/L for total cholesterol at 0 to 2 hours after the last meal, −0.2 mmol/L for LDL cholesterol at 0 to 2 hours, −0.1 mmol/L for HDL cholesterol at 0 to 5 hours, and 0.3 mmol/L for triglycerides at 1 to 4 hours after the last meal. This study demonstrated that lipid profiles vary only minimally in response to normal food intake in individuals in the general population. It was also concluded that nonfasting lipid profiles predicted an increased risk of cardiovascular events (Nordestgaard et al 2047-56).
Recently, various large prospective cohort studies and a meta-analysis have been published, investigating the possibility of a relationship between fasting and nonfasting serum triglycerides with cardiovascular disease. The studies demonstrated that fasting triglycerides augment the adjusted hazard ratios for cardiovascular disease risk 1.7 times as much (comparing upper with lower tertile), and nonfasting levels about 2.0 times as much (Stalenhoef, and De Graaf 355-61).
While patients are encouraged to make early morning appointments after fasting overnight, it isn’t feasible for every patient to comply with these guidelines established by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III). Based on one’s daily routine, eating habits, working day and sleeping pattern, some candidates may simply refuse to attain a lipid panel exam as they’re unable to fast for so long, while others may only partially comply with the requirements. Moreover, fasting for nine to twelve hours may not be possible for hospitalized patients who’re already in critical condition. While providers may find such noncompliance to skew the readings towards inaccuracy, fasting and nonfasting lipid levels are only notably different when measuring triglycerides. While guidelines propose measuring fasting lipids for initial screening of adults without cardiovascular disease, recent studies imply that nonfasting triglycerides are perhaps superior to fasting.
- Nordestgaard, Borge, Anne, Langsted and Jacob Freiberg. “Influence of Normal Food Intake on Lipids, Lipoproteins, Apolipoproteins, and Cardiovascular Risk Prediction.” Circulation. 118.20 (2008): 2047-56. Web. 15 Mar. 2012. <http://www.ncbi.nlm.nih.gov.jerome.stjohns.edu:81/pubmed?term=Influence of Normal Food Intake on Lipids, Lipoproteins, Apolipoproteins, and Cardiovascular Risk Prediction>.
- Stalenhoef, AF, and J De Graaf. “Association of fasting and nonfasting serum triglycerides with cardiovascular disease and the role of remnant-like lipoproteins and small dense LDL.” Current opinion in lipidology.. 19.4 (2008): 355-61. Web. 15 Mar. 2012. <http://www.ncbi.nlm.nih.gov.jerome.stjohns.edu:81/pubmed?term=Association of fasting and nonfasting serum triglycerides with cardiovascular disease and the role of remnant-like lipoproteins and small dense LDL>.
- “Which cholesterol test should you get? The number of tests has proliferated. But for most people, the traditional fasting cholesterol is still the way to go..” Harvard Health Letter. 30.1 (2004): 4-5. Web. 15 Mar. 2012. <http://www.ncbi.nlm.nih.gov.jerome.stjohns.edu:81/pubmed?term=Which cholesterol test should you get? >