Triglyceride levels measurement

Standard lipid screening to obtain a cholesterol profile for the risk of cardiovascular disease routinely reports total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Cholesterol values are reported in milligrams per deciliter of blood (mg/dL). Different organizations have made recommendations for normal cholesterol levels, but these must be interpreted carefully, as they are contingent on other risk conditions. For example, the recommendations for smokers or those with a family history of heart disease will be lower for someone without these conditions. The National Center for Cholesterol Education (NCEP) endorsed by the American Heart Association believes that LDL is the primary cholesterol component to determine therapy. LDL cholesterol accounts for 60—70% of blood serum cholesterol. An LDL less than 160 mg/dL is recommended for individuals with no more than one risk factor and less than 100 mg/dL for individuals with coronary heart disease. NCEP classifies HDL, which comprises between 20% and 30% of blood cholesterol, below 40 mg/dL as low. Triglycerides are an indirect measure of VLDL cholesterol. The NCEP considers a normal triglyceride level as less than 150 mg/dL. 

Recently, ingestion of purple juice for 14 days has been shown to improve endothelial function, as measured by flow-induced vasodilation, in patients with coronary artery disease [78]. The authors attributed this effect to the flavonoidic content of the purple juice. These benefits were observed despite use of antioxidant vitamins, lipid lowering medications and small increases in total cholesterol and triglycerides levels. 

Lipoprotein disorders are detected by measuring lipids in serum after a 10-hour fast. Risk of atherosclerotic heart disease increases with concentrations of the atherogenic lipoproteins, is inversely related to levels of HDL, and is modified by other risk factors (Table 35-1). Evidence from clinical trials suggests that LDL cholesterol levels of 60-70 mg/dL may be optimal for patients with coronary disease. Ideally, triglyceride levels should be below 150 mg/dL. Differentiation requires identification of the lipoproteins involved (Table 35-2). Diagnosis of a primary lipoprotein disorder usually requires further clinical and genetic data as well as ruling out secondary hyperlipidemias (Table 35-3). 

Primary increases of VLDL probably reflect a number of genetic determinants and are worsened by factors that increase the rate of VLDL secretion from liver, ie, obesity, alcohol, diabetes, and estrogens. A major indication for treatment is the presence of atherosclerosis in the patient or the patient s family. Treatment includes weight reduction, restriction of all types of dietary fat, and avoidance of alcohol. Fibrates or niacin usually produce further reduction in triglyceride levels if dietary measures are not sufficient. Marine omega fatty acids may also be of value. 

Lipids. Fasting plasma triglyceride levels provide some indication of fat metabolism, but arc again affected by a variety of metabolic priKcsscs. Essential fatty acid levels may be measured if specific deficiencies are suspected. Faecal fat may be measured both qualitatively and quantitatively in the assessment of malabsorption (pp. 104-105). 

Blood samples were withdrawn in patients fasting for 12 hours. Standard methods were used for measurement or uric acid (9) total cholesterol was determined using an enzymatic method (Coles-Cinet Scalvo, Siena, Italy). Triglyceride levels were determined using an enzymatic method (Boehringer). HDL-cholesterol was determined using a Dextran Mg sulfate method (Chol-HDL Sclavo, Siena, Italy). 

If a personal medical history, family history, and physical examination suggest the existence of a hyperlipoproteinemia, the next step is to measure blood levels of cholesterol and triglycerides. These measurements are made on blood drawn after an overnight fast during a steady state period in an individual s habits and environment. Elevated levels of cholesterol and/or triglycerides, or the presence of a creamy layer on the top of plasma after overnight refrigeration indicates to a physician the type of hyperlipo-... 

The level of apoB-containing lipoprotein particles is measured directly, mostly by immunonephelometric analysis of the plasma, on empty stomach or postprandially, whereas LDL cholesterol is mostly calculated indirectly as the difference of total cholesterol minus HDL-cholesterol and VLDL-cholesterol. In that respect, apo B can be considered a superior indicator of the global atherogenic risk over the sole quantification of LDL cholesterol and triglyceride levels, particularly in conditions of hypertriglyceridaemia characterized by high VLDL and low LDL levels. (JMB 2008, 27 148 -153). 

Often you need to carry forward data to a specific time point due to holes or sparseness of data. The previous example on determining baseline cholesterol level provides an excellent context for this problem. Assume that you have several cholesterol readings of HDL, LDL, and triglycerides for patients before they take an experimental pill designed to reduce cholesterol levels. For each cholesterol parameter, you want the last observation carried forward so long as the measures occur within a five-day window before the pill is taken. Here are some sample data that illustrate the problem ... 

Measurement of plasma cholesterol (which is about 3% lower than serum determinations), triglyceride, and HDL levels after a 12-hour or longer fast is important, because triglycerides may be elevated in nonfasted individuals total cholesterol is only modestly affected by fasting. 

Factors negatively affecting absorption of dietary fat may also be expected to negatively affect absorption of calcium. In the normal, healthy adult, dietary fat absorption is very efficient. However, such factors as level of dietary fat, fatty acid chain length, degree of fatty acid saturatedness, or triglyceride structure may have a measurable effect on calcium absorption under some circumstances. 

RP-HPLC with nonaqueous solvents and UVD at 246 nm was developed for the determination of low level POVs of vegetable oils. These measurements are specific for conjugated diene peroxides derived from vegetable oils with relatively high linoleic acid content. These measurements may be supplemented by nonspecific UVD at 210 nm and ELSD for detection of all eluted species. The elution sequence of the triglycerides in a nonaqueous RP-HPLC is linearly dependent on the partition number of each species, Vp, which is defined as = Nq — 2Ni, where Nq is the carbon number and is the double bond number. In the case of hydroperoxides = Nq — 2Nd — Vhpo, where Vhpo is the number of hydroperoxyl groups in the molecule (usually 1 for incipient POV). For... 

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