HDL Cholesterol Test
, LDL Cholesterol Test, Lipid Profile, Lipoprotein Analysis, Total Cholesterol Test, Triglycerides and Cholesterol Tests
Test Overview
Cholesterol and triglyceride tests are blood tests that
measure the total amount of fatty substances (cholesterol and
triglycerides) in the blood.
Cholesterol
travels through the blood attached to a
protein. This cholesterol-protein package is called a
lipoprotein. Lipoprotein analysis (lipoprotein profile or lipid profile)
measures blood levels of
total cholesterol,
LDL cholesterol,
HDL cholesterol, and triglycerides.
Cholesterol. The body uses cholesterol to
help build cells and produce
hormones. Too much cholesterol in the blood can build
up along the inside of the artery walls, forming what is known as
plaque. Large amounts of plaque increase your chances
of having a heart attack or stroke.
HDL (high-density lipoprotein) cholesterol
helps remove fat from the body by binding with it in the bloodstream and
carrying it back to the liver for disposal. It is sometimes called "good"
cholesterol. A high level of HDL cholesterol may lower your chances of
developing heart disease or stroke.
LDL (low-density lipoprotein) cholesterol
carries mostly fat and only a small amount of protein from the liver to other
parts of the body. It is sometimes called "bad cholesterol." A high LDL
cholesterol level may increase your chances of developing heart disease.
VLDL: (very low-density lipoprotein)
cholesterol contains very little protein. The main purpose of VLDL is to
distribute the triglyceride produced by your liver. A high VLDL cholesterol
level can cause the buildup of cholesterol in your arteries and increases your
risk of heart disease and stroke.
Triglycerides are a type of fat the body
uses to store energy. Only small amounts are found in the blood. Having a high
triglyceride level along with a high LDL cholesterol may increase your chances
of having heart disease more than having only a high LDL cholesterol
level.
Some medical experts recommend routine cholesterol and
triglyceride testing to screen for problems that affect the way cholesterol is
produced, used, carried in the blood, or disposed of by the body. Others may
choose to routinely measure only total cholesterol and HDL levels.
As part of a routine physical exam to screen for a
lipid disorder.
To check your response to medicines used to treat lipid
disorders.
To help determine your chances of having of heart disease,
especially if you have other risk factors for heart disease or symptoms that
suggest heart disease is present.
If you have unusual symptoms, such as yellow fatty deposits in
the skin (xanthomas), which may be caused by a rare genetic disease that causes
very high cholesterol levels.
How To Prepare
Preparation depends on the test. Ask
your doctor which test you are having. For example, you can get a total
cholesterol test or direct LDL test at any time, even if you recently had a
meal or a snack. But you will likely not eat for a few hours before a test that
measures LDL, HDL, and triglycerides.
If your doctor tells you to fast before your test, do not eat or
drink anything except water for 9 to 12 hours before having your blood drawn.
Usually, you are allowed to take your medicines with water the morning of the
test. Fasting is not always necessary, but it may be recommended.
Do not eat high-fat foods the night before the test.
Do not drink alcohol or exercise strenuously before the
test.
Many medicines may affect the results of this
test. Be sure to tell your health professional about all the nonprescription
and prescription medicines and herbs or natural substances you take.
Tell your health professional if you have had a test such as a thyroid or
bone scan that uses a radioactive substance within the last 7 days.
Talk to your health professional about any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
indicate. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?)
.
How It Is Done
The health professional taking a sample
of your blood will:
Wrap an elastic band around your upper arm to stop the flow of
blood. This makes the veins below the band larger so it is easier to put a
needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. More than one needle stick may be
needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is
collected.
Put a gauze pad or cotton ball over the needle site as the needle
is removed.
Put pressure on the site and then put on a bandage.
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
pinch.
Risks
There is very little chance of a problem from
having blood sample taken from a vein.
You may get a small bruise at the site. You can lower the chance
of bruising by keeping pressure on the site for several minutes.
In rare cases, the vein may become swollen after the blood sample
is taken. This problem is called phlebitis. A warm compress can be used several
times a day to treat this.
Ongoing bleeding can be a problem for people with bleeding
disorders. Aspirin,
warfarin (Coumadin), and other
blood-thinning medicines can make bleeding more likely. If you have bleeding or
clotting problems, or if you take blood-thinning medicine, tell your health
professional before your blood sample is taken.
Results
Cholesterol and triglyceride tests are
blood tests that measure the total amount of fatty substances (cholesterol and
triglycerides) in the blood.
Results are
usually available within 24 hours.
Cholesterol and triglyceride
levels vary according to your age and sex. Results may also vary from lab to
lab.
* The figures in this table
are provided by the National Cholesterol Education Program (NCEP) of the
National Institutes of Health (NIH).
An HDL level of 60 mg/dL (1.5 mmol/L) or higher protects against
heart disease.
HDL cholesterol levels of 40 mg/dL (1.0 mmol/L) or lower increase
your risk of developing heart disease, especially if you also have high total
cholesterol levels.
Very high cholesterol and triglyceride levels may be caused by an
inherited form of high cholesterol (hypercholesterolemia or
hyperlipidemia).
If you have a very high risk of having a heart attack, your
doctor may want your LDL level to be less than 70 mg/dL. You have a very high
risk if you smoke and have
coronary artery disease, or if you have coronary
artery disease and
diabetes,
acute coronary syndrome, or
metabolic syndrome.
Many conditions can affect cholesterol and triglyceride
levels. Your health professional will talk with you about any abnormal results
that may be related to your other health problems.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
Pregnancy. Values are the highest during the third
trimester and usually return to the prepregnancy
levels after delivery of the baby.
What To Think About
Having a high cholesterol level increases your chances of having
a heart attack. The higher your cholesterol, the greater your chances. An
elevated total cholesterol level in younger people is particularly significant,
since the narrowing of the
coronary arteries usually takes many years to
develop.
Lifestyle changes (such as diet changes, weight loss, and
exercise) may help lower blood cholesterol levels and increase HDL ("good")
cholesterol. Some people have better responses to diet and lifestyle changes
than do others. Lifestyle changes might include:
Reducing saturated (animal) fats and cholesterol in the diet
while increasing fiber and complex
carbohydrate.
Losing weight. An improvement may occur if you lose as little
as 5 lb (2.5 kg) to
10 lb (4.5 kg).
Moderate consumption of alcohol can also increase HDL
cholesterol.
Moderate alcohol consumption means no more than 2 drinks per
day for men or 1 drink per day for women; 1 drink is
12 fl oz (350 mL) of beer,
5 fl oz (150 mL) of wine, or
1.5 fl oz (45 mL) of
liquor.
The National Cholesterol Education Program (NCEP) has developed a
risk assessment calculator to estimate your risk of having a heart attack or
dying from
coronary artery disease (CAD) over 10 years. This tool
is designed to estimate risk in adults age 20 and older who do not have heart
disease or diabetes. Use the
Interactive Tool: Are You at Risk for a Heart Attack?
to calculate your risk of coronary artery disease.
Talk with your doctor about other things that raise your risk for
heart problems. Your doctor may change your goals for cholesterol levels if you
have other risk factors for coronary artery disease, such as:
You are a man and older than 45, or you are a woman and older
than 55.
Talk to your health professional about which cholesterol
screening is best for you. Medical experts disagree about routine screening for
lipid disorders.
Cholesterol screening is often available in supermarkets,
pharmacies, shopping malls, and other public places. Home cholesterol testing
kits also are available. The results of tests done outside a doctor's office or
lab may not be accurate. If you have cholesterol screening done outside your
doctor's office, talk with your doctor about the accuracy of the
results.
Fischbach FT, Dunning MB III, eds. (2004).
Manual of Laboratory and Diagnostic Tests, 7th ed.
Philadelphia: Lippincott Williams and Wilkins.
Genest J, et al. (2003). Recommendations for the
management of dyslipidemia and the prevention of cardiovascular disease:
Summary of the 2003 update. Canadian Medical Association Journal, 169(9): 921-924. Also available online:
http://www.cmaj.ca/cgi/content/full/169/9/921/DC1.
Handbook of Diagnostic Tests
(2003). 3rd ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2002). Mosby's Manual of Diagnostic and Laboratory Tests, 2nd ed. St. Louis:
Mosby.
Credits
Author
Maria G. Essig, MS, ELS
Author
Robin Parks, MS
Editor
Kathleen M. Ariss, MS
Editor
Susan Van Houten, RN, BSN, MBA
Associate Editor
Tracy Landauer
Primary Medical Reviewer
E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer
Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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Cholesterol and triglyceride tests are blood tests that
measure the total amount of fatty substances (
