A cholesterol test (or lipid fat profile) is a group of simple blood tests that reveal important information about the types, amount and distribution of the various types of fats (lipids) in the bloodstream. To give this valuable information, a complete blood fat profile measures:

• Lipids. The two main types of lipids in the bloodstream are:
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  • Cholesterol. A waxy fat that is present in all human beings. The body uses cholesterol to assist in the manufacture of hormones or vitamin D, to build cell walls, and produce bile, which breaks down other fats. There are two sources of cholesterol in the human body. The liver manufactures about 80 percent of cholesterol found in the body. In addition, people consume cholesterol by eating animal products such as meat, eggs and dairy products. When cholesterol levels get too high, the excess cholesterol is deposited on the inside walls of arteries in the form of plaque. A buildup of plaque eventually narrows the arteries, a condition known as atherosclerosis, which can lead to coronary disease artery and/or a heart attack.
    
    
    
     
  • Triglycerides. Another type of fat in the bloodstream. Triglycerides are extremely common, accounting for 95 percent of the body’s fatty tissue. High triglyceride levels are associated with certain risk factors for coronary artery disease, including low HDL “good” cholesterol levels. Many people with high LDL “bad” cholesterol levels also have high triglyceride levels.
  
  
• Apolipoproteins. Both cholesterol and triglycerides are transported through the bloodstream by certain proteins called apolipoproteins. If apolipoprotein testing is performed as part of a cholesterol test, then two types of apolipoprotein will be measured: Apolipoprotein B100 (Apo-B) and Apolipoprotein CII (Apo-C-II). Apo-B has shown to be particularly helpful in determining cardiovascular risk in women.
  
  
• Lipoproteins. Cholesterol and triglyceride levels are obtained by measuring the various lipoproteins. A lipoprotein is created when apolipoprotein wraps around the fat, thus creating a package. The  four types of lipoproteins are:
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  • HDLs. These move easily through the blood and are beneficial to the body. They are stable and do not stick to artery walls. They help prevent heart disease by carrying cholesterol away from the arteries and back to the liver, where the process of its removal from the body begins.
    
    
  • LDLs. These contain more fat and less protein than HDLs. LDLs are unstable, and they tend to fall apart. Rather than being removed from the body by the liver, they stick to (and can damage) cells lining the inside of artery walls. Areas of cell damage provide a magnet-like attraction for other fatty substances (e.g., triglycerides), sticky blood-clotting materials (e.g., fibrin and platelets) and white blood cells. The waxy accumulation of these materials is plaque, which can eventually lead to atherosclerosis or coronary artery disease. 
    
    
  • “Very bad” or very low-density lipoproteins (VLDL). These lipoproteins contain mostly lipids with few proteins. VLDLs and so-called intermediate-density lipoproteins (IDLs) belong to a newer category known as non-HDL cholesterol. Studies show that high non-HDLs can raise the risk of non-fatal heart attack and angina among individuals who already have heart disease.
    
    
  • Chylomicrons. These lipoproteins are rich in triglycerides and very low in protein.

By analyzing lipids, apolipoproteins and lipoproteins, cholesterol tests are important indicators of the patient’s risk of developing heart disease or other health problems. Therefore, a cholesterol test is commonly performed as part of a full  coronary profile risk. Most patients will be screened at regular intervals as a part of their prevention plan. Patients diagnosed with hypercholesterolemia (high cholesterol) or other blood fat disorders will have profiles performed more often to monitor the effectiveness of treatment.

Cholesterol tests are often performed in a physician’s office or other clinical setting. However, individuals who need to test their total cholesterol frequently may choose to purchase home testing equipment.