Methods for Triglycerides Determination - Postprandial Lipemia
In the previous section, we analyzed the process of atherosclerosis and its acceleration when postprandial triglyceride levels in plasma are increased. Until now we used to measure fasting and non-fasting triglyceride levels.
The instructions for measuring triglycerides until recently were the following:
• Sampling for fasting triglyceride levels should be taken after a 12-14h of fasting
• Sampling for non-fasting triglyceride levels should be taken without any preparation- precaution, any time of the day, but within 8-14h following ordinary meal consumption.
Morning samples for fasting triglyceride level determination cannot record the pathological postprandial triglyceride levels due to the long period of fasting.
Non-fasting triglyceride levels may vary according to the:
• Quantity of the meal
• Fat content of the meal
• Time determination (first, second or third meal)
• Carbohydrate content of the meal
• Time after the meal, etc.
During the day we consume 3-4 meals each one containing 20-40g fat. As a result, the Cumulative triglyceride levels in circulation during the day are above fasting triglyceride levels (/day of 20-40g fat each one).
Furthermore, cumulative increased levels of triglycerides are observed after the second, third or fourth meal, since increased postprandial triglyceride levels begin from an already elevated level of the previous meal or meals.
So, during the day, there are high triglyceride levels, which cannot be determined after a morning sample.
As a result, postprandial determination of triglyceride levels is crucial.
Postprandial triglyceride level determination is supported by large clinical studies:
• The Women's Health Study 
• The Copenhagen City Heart Study 
• The Physicians Health Study 
• The Apolipoprotein-related Mortality Risk Study 
• The Second Northwick Park Heart Study 
• The Norwegian Study
• The EARS II study 
• the ARIC study 
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2. Nordestgaard BG, Benn M, Schnohr P, Tybjaerg-Hansen A. Non fasting triglycerides and risk of myocardial infarction, ischemic heart disease, and death in men and women. JAMA 2007; 298: 299-308.
3. Stampfer MJ, Krauss RM, Ma J, et al. A prospective study of triglyceride level, low-density lipoprotein particle diameter, and risk of myocardial infarction. JAMA 1996; 276: 882-8.
4. Talmud PJ, Hawe E, Miller GJ, Humphries SE. Non fasting apolipoprotein B and triglyceride levels as a useful predictor of coronary heart disease risk in middle-aged UK men. Arterioscler Thromb Vasc Biol 2002; 22: 1918-23.
5. Waterworth DM, Talmud PJ, Bujac SR, Fisher RM, Miller GJ, Humphries SE. Contribution of apolipoprotein C-III gene variants to determination of triglyceride levels and interaction with smoking in middle-aged men. Arterioscler Thromb Vasc Biol 2000; 20:2663-9.
6. Stensvold I, Tverdal A, Urdal P, Graff-Iversen S. Non-fasting serum triglyceride concentration and mortality from coronary heart disease and any cause in middle aged Norwegian women. BMJ 1993; 307: 1318-22.
7. Tiret L, Gerdes C, Murphy MJ, Dallongeville J, Nicaud V, O'Reilly DS, Beisiegel U, De Backer G. Postprandial response to a fat tolerance test in young adults with a paternal history of premature coronary heart disease - the EARS II study (European Atherosclerosis Research Study). Eur J Clin Invest. 2000 Jul;30(7):578-85
8. Sharrett AR, Chambless LE, Heiss G, Paton CC, Patsch W. Association of postprandial triglyceride and retinyl palmitate responses with asymptomatic carotid artery atherosclerosis in middle-aged men and women. The Atherosclerosis Risk in Communities (ARIC) Study. Arterioscler Thromb Vasc Biol. 1995 Dec;15(12):2122-9.
Determination of postprandial triglyceride level, after the consumption of a special meal (LIPOTEST meal) is the Fat Tolerance test.
For historical reasons, it is worthy to mention that since 1979 Zilversmit was the first who believed that atherogenesis is a postprandial phenomenon and emphasized the need of postprandial triglyceride level determination.
Many clinical studies that followed confirmed the value of postprandial triglyceride level determination and also showed that elevated levels are observed in patients with:
• coronary heart disease
• type 2 diabetes mellitus
•obese (BMI)> 27kg/m2
• in patients with metabolic syndrome
• in women after menopause
• the elderly over 65 years
• also, elevated postprandial triglyceride levels observed in smokers (even with normal fasting triglyceride levels), may contribute to increased risk for cardiovascular events in this population.