Hypertriglyceridemia is a serum lipid disorder (dyslipidemia) defined by serum triglyceride levels of ≥150 mg/dL. It is associated with an increased risk of cardiovascular diseases, such as coronary artery disease, or acute risk of pancreatitis if TG levels exceed 500 mg/dL. The prevalence of hypertriglyceridemia among the population in the Western World is estimated to reach up to 30% of the population, caused by genetic predisposition and various secondary/contributing factors, such as lifestyle and dietetic behavior (e.g. obesity, malnutrition, metabolic syndrome), as well as by numerous diseases (e.g. diabetes, renal disease, autoimmune diseases). It is estimated that there are 5 million patients in the U.S. with TG levels ≤ 500 mg/dL. A recent NHANES analysis of dyslipidemia in the US indicated that LDL levels have actually declined since that last NHANES analysis, but the percentage of patients with severe hypertriglyceridemia has risen sharply along with the dramatic increases in obesity.
Dyslipidemia is a disorder of lipid metabolism. This term is often used as a blanket term to describe any imbalance in the level of blood lipids; thus, it is often used to describe a variety of conditions characterized by either excessively high or excessively low levels of certain lipids in the bloodstream. These lipids consist of cholesterol, cholesterol esters, phospholipids and triglycerides. Lipids are transported in blood plasma as part of larger molecules called lipoproteins. The five major families of plasma lipoproteins are:
• Very low-density lipoproteins (VLDL);
• Low-density lipoproteins (LDL);
• Intermediate-density lipoproteins (IDL);
• High-density lipoproteins (HDL).
In addition, there are apolipoproteins (Apo), which are proteins particularly formed in the liver and the intestine. These proteins play an important role in the production, transport and uptake of cholesterol in the body.
The second most common form of dyslipidemia is mixed dyslipidemia, with the physicians estimating that between 22% and 37% have these forms of dyslipidemia.
The term mixed dyslipidemia refers to a condition in which the patient suffers from hypercholesterolemia, low HDL-C and hypertriglyceridemia. Due to the nature of the condition and the fact that different classes of antidyslipidemics offer different benefits in controlling lipid abnormalities, a combination therapy is often considered the most beneficial in patients with mixed dyslipidemia. Options are a combination of a statin with either fibrate or nicotinic acid or Omega-3 fatty acids.
The majority of the fat exists in food as well as in the body in the form of triglycerides. Hormones regulate the release of TGs from fat tissue so that they meet the body’s needs for energy between meals. According to the revised classification of ATP III, TG levels lower than 150 mg/dL are considered normal.
The emphasized role of elevated triglycerides as a risk marker in ATP III, especially when associated with low levels of HDL-C, is due to the growing awareness of the causes and consequences of the metabolic syndrome (combination of disorders leading to an increased risk of developing cardiovascular disease and diabetes) and type 2 diabetes mellitus, as well as the effective secondary prevention of MI and reduced mortality as shown in many trials.
Table: Classifications of serum triglycerides according to the NCEP guidelines from 2001 (ATP III: no authors listed, 2002).