Definition
- Triglycerides are a form of fat and a major source of energy for the body. Most triglycerides are stored in adipose tissue as glycerol, monoglycerides, and fatty acids, and the liver converts these to triglycerides. Following eating, increased levels of triglycerides are found in the blood. Triglycerides move via the blood from the gut to adipose tissue for storage. Most triglycerides are carried in the blood by lipoproteins. Of the total triglycerides, about 80% are in VLDLs and 15% in LDLs, which play an important role in metabolism as energy sources and transporters of dietary fat.
- Normal ranges: see Table 16.80.
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TABLE 16 " “80National Cholesterol Education Program Guidelines for Triglycerides*View LargeTABLE 16 " “80National Cholesterol Education Program Guidelines for Triglycerides* Triglyceride Level (mg/dL) Category <150 Normal 150 " “199 Borderline-high 200 " “499 High ≥500 Very high *These values are based on fasting plasma triglyceride levels.
Use
- Elevated levels of triglycerides in the blood are associated with an increased risk of developing cardiovascular disease and arteriosclerosis.
Interpretation
- Concentrations associated with certain disorders:
- Less than 150 mg/dL not associated with any disease state
- 250 " “500 mg/dL associated with peripheral vascular disease; may be a marker for patients with genetic forms of hyperlipoproteinemias who need specific therapy
- Greater than 500 mg/dL associated with high risk of pancreatitis
- More than 1,000 mg/dL associated with hyperlipidemia, especially type I or type V; substantial risk of pancreatitis
- Greater than 5,000 mg/dL associated with eruptive xanthoma, corneal arcus, lipemia retinalis, enlarged liver and spleen
Increased In
- Hyperlipoproteinemia types I, IIb, III, IV, and V
- Glycogen storage disease (von Gierke disease)
- Diabetes
- Hypothyroidism
- Nephrosis, chronic renal disease
- Pancreatitis
- Liver disease, alcoholism
- Werner syndrome
- Down syndrome
- Myocardial infarction
- Gout
Decreased In
- Abetalipoproteinemia
- Malnutrition
- Hyperthyroidism
- Hyperparathyroidism
- Malabsorption syndrome
Limitations
- Factors that increase triglyceride levels include food and alcohol intake (should be 12-hour fast [24 hours for alcohol]); corticosteroids, protease inhibitors for HIV, beta blockers, and estrogens; pregnancy; acute illness; smoking; and obesity.
- Factors that decrease triglyceride levels include exercise and weight loss.
- Diurnal variation causes triglycerides to be lowest in the morning and highest around noon.
Other Considerations
- Serum for triglyceride and for calculating LDL-C should follow a 12-hour fast.
Suggested Reading
1National Institutes of Health, National Heart Lung and Blood Institutes National Cholesterol Education Program. http://www.nhlbi.nih.gov/about/ncep/. Accessed November 18, 2010.