Total cholesterol, HDL, and LDL
Cholesterol is a lipid (fat) in the bloodstream. Cholesterol comes from two main sources. It is produced in the liver and contained in certain foods. This substance is essential for the body to work properly. When there is too much cholesterol in the body, it accumulates on the walls of the blood vessels, making it harder for blood to reach the organs and potentially causing a heart attack, stroke, or other issues. Higher cholesterol levels are associated with an increased risk of developing cardiovascular disease.
Cholesterol is transported through the body by lipoproteins. LDL and HDL are the two main types of lipoproteins. LDL transports cholesterol from the liver to other parts of the body. It's often referred to as "bad" cholesterol since elevated LDL is a risk factor for cardiovascular disease. However, HDL gathers up cholesterol in the body and carries it to the liver for elimination. It is known as "good" cholesterol. Maintaining a balance between these types of cholesterol is essential for cardiovascular health.
Total cholesterol, composed mainly of LDL and HDL, is one of the elements used to estimate the risk of cardiovascular disease. Age, gender, blood pressure, smoking, diabetes and HDL are also considered in estimating cardiovascular disease risk. Depending on the cardiovascular risk obtained, lifestyle changes and treatment may be considered.
| What is the purpose of this test? |
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| How to prepare? |
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| Reference values |
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| Associated tests | Related tests include the following:
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| How is it done? | Blood sample, usually taken from a vein in the arm. |
| How long before I get the results? | Results are usually ready in a day. It may take longer to receive your results. |
What does an abnormal test result mean?
High values of total cholesterol and LDL:
- Increased risk of cardiovascular disease.
- LDL levels can be elevated for various reasons:
- Family history
- Smoking
- Obesity
- Poor diet
- Not enough exercise
High values of HDL cholesterol:
- Generally beneficial to have a high result.
- LDL levels can be elevated for various reasons:
- Exercising
- Weight loss
- Quitting smoking
- Reasonable alcohol consumption
Low values of LDL cholesterol and total cholesterol:
- Since it means lower risk of cardiovascular disease, a lower result is generally desirable.
- However, low LDL cholesterol could also be caused by the following:
- Certain genetic diseases
- Certain cancers
- Chronic anemia
- Hyperthyroidism
Medications that may affect test results
The use of certain medications can influence test results. Here are a few examples:
- Corticosteroids (e.g., prednisone)
- Certain blood pressure medications
- Sex hormones (e.g., estrogen, testosterone)
- Oral retinoids (e.g., isotretinoin)
- Certain HIV medications
Factors that can interfere with test accuracy
Certain factors may influence test results. Here are a few examples:
- Cholesterol levels may temporarily drop in the event of acute illness, heart attack, or severe stress.
- It's best to wait for at least six weeks after the event to obtain a more accurate measurement.
- A measurement bias can affect LDL cholesterol when triglyceride levels exceed 1.5 mmol/L.
- Other measurements, such as non-HDL-cholesterol or apolipoprotein B, offer more reliability.
What you should know before going for this test
When you go in for a blood test or any other medical exam, it's always a good idea to bring a complete list of any prescriptions, over-the-counter medications, or natural health products you're taking. Unless otherwise advised, it's best to take your medications as usual on blood test days. If in doubt, don't hesitate to talk to your healthcare professional.
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.