Definition

The High Density Lipoprotein (HDL) test is designed to measure the levels of HDL cholesterol in the blood. HDL cholesterol is a combination of cholesterol, phospholipids, and proteins, which are produced and secreted by the liver and the intestines. HDL cholesterol is often referred to as “good cholesterol” because it helps transport excess cholesterol that accumulates in the blood vessels. This cholesterol is then carried to the liver, where it is metabolized, preventing dangerous build-up in the arteries.

Higher HDL values are considered beneficial and serve as a protective factor against heart disease. The HDL test is valuable for assessing the potential risk of atherosclerosis (fatty plaque build-up in the blood vessels) and coronary heart disease.

Indication

This test is typically performed under the following circumstances:

• To aid in diagnosing dyslipidemia (elevated cholesterol levels in the body) or metabolic syndrome (a group of conditions related to metabolic disorders).

• To monitor the effectiveness of treatment for dyslipidemia or metabolic syndrome.

• As part of routine screening during medical check-ups.

• To evaluate and assess the risk factors associated with coronary heart disease.

• For routine screening or assessment of lipid profiles.

Contraindication

There are no specific contraindications or medical conditions that would prevent someone from undergoing this test.

Preparation Before the Test

No specific preparation is required before undergoing an HDL test. This test can be performed without fasting. However, if the HDL value is needed to calculate the LDL level, fasting is recommended. This is because the calculation of LDL requires triglyceride levels, and fasting ensures that the triglyceride value reflects the body's true condition.

Typically, the HDL test is performed alongside other cholesterol tests, such as those for triglycerides, LDL, and total cholesterol. To simplify the process, it is advisable to fast for at least 12 hours before the test. However, it’s important to note that whether or not you fast does not significantly affect the HDL value.

Test Procedure

The HDL test generally requires a blood serum sample of between 0.25 to 0.5 ml. This sample is obtained from a vein and placed into a specialized collection tube. Laboratory staff performing the test will wear appropriate gloves and personal protective equipment (PPE).

Before collecting the blood sample, the technician will apply an elastic band around the arm and cleanse the needle puncture area with antiseptic gauze. The blood is typically drawn from the area near the elbow crease. Once the blood has been collected into the special tube, the elastic band will be removed, and the puncture site will be pressed and cleaned with antiseptic gauze. This test procedure is quick, usually taking only a few minutes. The blood sample is then analyzed using specialized equipment in the laboratory, and results are typically available within a few hours.

Normal and Abnormal Values

The normal range for HDL levels varies by age and gender. Generally, the following values are used to interpret HDL test results:

Based on guidelines from The National Lipid Association and the National Cholesterol Education Program (NCEP), the normal values for adults are as follows:

For adult males:

For adult females:

According to the guidelines from the Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents, for children aged 2–17 years:

Results and Recommendations (Follow-up Tests)

High HDL Results

If your HDL test results show a high value, it generally indicates that you have been maintaining a healthy lifestyle. High HDL levels are strongly linked to a reduced risk of heart and blood vessel diseases.

Certain medical conditions or factors associated with high HDL levels include hyperalphalipoproteinemia, regular physical activity or exercise, chronic liver disease, and weight loss.

However, very high HDL levels (above 100 mg/dL) may be linked to an increased risk of heart disease. Therefore, if your HDL levels are extremely high, it is important to consult a doctor for further evaluation.

The Centers for Disease Control and Prevention (CDC) recommends that adults aged 20 and older undergo routine cholesterol checks, including HDL tests, every 5 years, as total blood cholesterol levels begin to rise and HDL cholesterol levels tend to decrease with age. For men aged 45-65 and women aged 55-65, it is suggested to have an HDL test annually or every two years.

Medline Plus suggests that children should undergo their first HDL test between the ages of 9-11 years, followed by tests every 5 years. If a child has a family history of high cholesterol, heart disease, or stroke, it is advised that they begin testing as early as age 2.

Low HDL Results

If your HDL test results indicate low values, it is important to seek further consultation with a doctor. Low HDL values are strongly associated with the risk of heart and blood vessel diseases, particularly coronary heart disease. Additionally, low HDL levels are often observed in individuals with metabolic syndrome, which includes a combination of conditions such as obesity, high blood pressure, and elevated blood sugar levels.

Other medical conditions that may lead to low HDL values include liver disease, chronic kidney disease, malnutrition, a sedentary lifestyle, smoking, or the use of certain medications such as beta blockers, diuretics, or steroids.

For those with low HDL values, doctors often recommend weight loss and increasing daily physical activity (at least 30 minutes of exercise for 3-5 days per week) as these actions can help raise HDL levels. In addition, avoiding foods high in fats (such as cakes and cookies), refraining from smoking, and reducing or eliminating alcohol consumption can also aid in boosting HDL levels.

HDL values lower than 5 mg/dL can indicate Tangier disease, which is frequently associated with liver disease or dysfunction in liver cells.

Consult the Right Doctor

Adults with abnormal HDL test results should consult with a general practitioner for further tests or to begin appropriate treatment. For more specialized advice, individuals may also consult a cardiologist, internist, or metabolic-endocrinology expert to address their HDL-related concerns. For pediatric patients, any abnormal test results should be discussed with a pediatrician.

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