HDL Cholesterol Test

Other names: High-Density Lipoprotein Cholesterol; ’Good’ Cholesterol; HDL; HDL-C;

HDL (high density lipoprotein) is commonly known as ’good’ cholesterol; it helps to carry cholesterol around the body and takes excess amounts of cholesterol to the liver so that they can be excreted (LDL, ’bad’ cholesterol contributes to fatty deposits sticking to the walls of the arteries). The HDL test measures the amount of HDL in the blood; low levels of HDL, coupled with high levels of LDL, may indicate a high risk of heart disease.

Why is the test used?

The test is primarily used to assess an individual’s risk of developing heart disease.

The HDL test is usually ordered along with other tests, including total cholesterol and lipid profile. If levels of cholesterol are high because the individual has a high concentration of HDL, this does not usually mean the person is at high risk of developing heart disease.

The test is usually ordered for a patient who has symptoms of heart disease or risk factors for heart conditions; risk factors include family history of heart disease, high blood pressure, obesity, heavy drinking, smoking and age (risk increases as a person gets older; men over the age of 45 and women over the age of 55 generally have a higher risk of developing heart disease).

How is the test done?

The test is done by collecting and analysing a blood sample; a needle is inserted into a vein in the arm (usually on the inside of the elbow) and the blood is drawn out and collected in a syringe. Once the sample has been collected, it will placed in a bottle, labelled with the patient’s name and sent to the laboratory for analysis.

In some cases, a sample may be collected from the fingertip; a needle is used to prick the skin and the blood is collected. In infants, the same technique may be used to obtain a sample from the heel.

It is usually necessary to fast for a period of time before the test is carried out (usually between 8 and 12 hours).

What do the test results mean?

If levels of HDL are high, this indicates that the individual has a low risk of developing heart disease. HDL levels are recorded in two forms; as a percentage and as a measurement. If levels of HDL are less than 20% of the total cholesterol, this indicates that there is a higher risk of heart disease; if levels are 20% this represents an average risk and if levels are higher than 20% of total cholesterol, this indicates that there is a low risk of heart disease. A desirable measurement for HDL is more than 1.0mmol/L for males and more than 1.2 mmol/L for females.

It is important that the test is not carried out if the patient is unwell, as this can affect the results. If a patient has been unwell, the test should not be carried out until around six weeks later.

Levels of HDL may decrease in response to an acute illness, stress or trauma.

Pregnancy can affect HDL levels so the test is usually not carried out until after 6 weeks after the baby is born.

Specific Blood Tests

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