Cholesterol Tests

What is cholesterol?

Cholesterol is a waxy, fatlike substance that is naturally present in cell walls or membranes everywhere in the body. Your body uses cholesterol to produce many hormones, vitamin D, and the bile acids that help to digest fat. If you have too much cholesterol in your bloodstream, the excess may be deposited in the arteries of the heart, which could lead to heart disease.

What is a cholesterol test?

A cholesterol test is a simple blood test that checks the cholesterol levels in your blood. This test is also called a fasting lipoprotein profile. A fasting lipoprotein profile measures:

• Total cholesterol (the total amount of cholesterol in your blood)



• HDL (“good”) cholesterol (helps keep cholesterol from building up in your arteries)



• LDL (“bad”) cholesterol (main cause of buildup and blockage in your arteries)



• Triglycerides (another form of fat that may also lead to blockage in your arteries)

A cholesterol test is done to evaluate a person’s risk for heart disease. Government guidelines state that healthy adults who are aged 20 years or older should have a cholesterol test done once every 5 years.

With the fasting lipoprotein profile, you will be instructed to not eat or drink (except for water) for 14 hours before the test, and to abstain from alcohol for 48 hours.

A cholesterol test can be done without fasting, but then only the levels of total cholesterol and HDL (“good”) cholesterol can be used.

During this procedure, a blood sample will be taken from a vein in your arm. To do so, a tourniquet (an elastic band) is tied around your arm just above the elbow. A needle is then inserted into a vein in your arm near the inside of your elbow. Once the needle is positioned, a small amount of blood is withdrawn and collected in a vial or a syringe. After the blood is collected, the needle is removed from the vein, and the tourniquet is removed from your arm. A small cotton ball is pressed over the puncture site to stop any bleeding. After the bleeding has stopped, a bandage is put on. 

How long does it take?

This is a short procedure, usually only lasting 3 minutes or less.

Does it hurt?

Most people feel only mild pain as the needle is advanced under the skin into the vein.

After the procedure, you can resume your normal activities, including your regular diet if you fasted. If you stopped taking any medicines prior to this procedure, your doctor will advise you as to when you can start taking them again.

There is very little risk associated with taking blood from a vein in the arm, although there is a slight risk of infection anytime the skin is broken. 

A bruise may develop in the area where the needle was inserted. Sometimes, a hematoma can develop at the puncture site. A hematoma is a large accumulation of blood underneath the skin, whereas a bruise is a small accumulation of blood underneath the skin. If you think you may have a hematoma and it appears to be growing larger, put manual pressure over the site, which should stop the bleeding after several minutes. If it does not stop, you should contact your doctor. 

Continued or excessive bleeding is a possible risk, especially for those people with bleeding disorders. People who take blood-thinning medicines are at more of a risk of developing a hematoma.

Some people may feel lightheaded after having a blood sample taken. Lying down or having something to eat or drink can usually treat lightheadedness. People who feel lightheaded may faint, but this is rare.

The blood is sent to a laboratory for analysis. The results from a fasting lipoprotein profile are usually available a few days to a week following the procedure. Your doctor will interpret your cholesterol levels and then discuss them with you. You and your doctor will also discuss any treatment that is required based on these results.

• Total cholesterol will fall into 1 of 3 categories: desirable (less than 200 mg/dL), borderline high risk (200-239 mg/dL), or high risk (240 mg/dL and above).
  
  
• HDL cholesterol will fall into 1 of 3 categories: 60 mg/dL and above, which is thought to protect you against heart disease; 40-59 mg/dL, which is better; or 40 mg/dL and less, which is considered to be a major risk factor for heart disease.
  
  
• LDL cholesterol will fall into 1 of 5 categories: optimal (less than 100 mg/dL), near optimal/above optimal (100-129 mg/dL), borderline high (130-159 mg/dL), high (160-189 mg/dL), or very high (190 mg/dL and above).
  
  
• Triglycerides will fall into 1 of 4 categories: normal (less than 150 mg/dL), borderline high (150-199 mg/dL), high (200-499 mg/dL), or very high (500 mg/dL and above).

The risk of cardiovascular disease associated with these levels of cholesterol and triglycerides will depend upon the presence or absence of other risk factors, such as the presence of known cardiovascular disease (eg, prior heart attack or stroke), hypertension, diabetes, cigarette smoking, age, sex, and positive family history. Thus, cardiovascular risk and treatment options must be considered in light of your overall cardiovascular risk profile.

You will need to discuss the results of your test with your doctor to understand your risk of heart and vascular disease and to determine if you should change your diet or take medications. It is important to realize that medicines that lower cholesterol definitely reduce the risk of heart disease and are safe if taken and monitored properly.

|Web Links|

High Cholesterol
 
American Heart Association
 
National Cholesterol Education Program, Live Healthier, Live Longer – Cholesterol Counts for Everyone
 
National Cholesterol Education Program, Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III)
 
National Cholesterol Education Program, High Blood Cholesterol – What You Need to Know
 
MEDLINEplus Health Information, US National Library of Medicine and National Institutes of Health, Cholesterol

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Author: Gary E Sander, MD, PhD, Professor, Department of Internal Medicine, Division of Cardiology, Louisiana State University School of Medicine and Medical Center.

Coauthor(s): Lauri Graham, Medical Writer, .com, Inc.

Editors: Alan D Forker, MD, Program Director of Cardiovascular Fellowship, Professor of Medicine, Department of Internal Medicine, University of Missouri at Kansas City School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, ; Michael E Zevitz, MD, Clinical Assistant Professor, Department of Medicine, Rosalind Franklin University of Medicine and Science, Chicago.