Triglyceride level
Alternative names:
TG; triacylglycerol
How the test is performed:
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test:
Fast for 8 to 12 hours before the test. The health care provider may advise you to withhold drugs that may affect the test (see special considerations).
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed:
Triglycerides are often measured as a reflection of fat (lipid) ingestion and metabolism, and/or as part of an evaluation of coronary risk factors.
Triglycerides comprise the largest proportion of fats (lipids) in the diet, in the adipose tissue, and in the blood. Immediately after a meal, triglycerides appear in the blood as the major constituent of chylomicrons. Under normal circumstances, triglycerides within chylomicrons are stripped of fatty acids as they pass through various tissues (especially adipose and skeletal muscle). The chylomicron remnant is then taken up by the liver so that chylomicrons disappear from the blood within 2 or 3 hours. The remaining triglycerides, plus additional triglycerides synthesized within the liver, are then repackaged as VLDL and secreted into the blood from the liver.
Triglycerides are a storage form of energy. They are stored in adipose tissue and muscle, and gradually released and metabolized between meals according to the energy needs of the body.
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