Direct LDL-C

Also Known As

Direct LDL-C

Direct LDL

DLDL

LDL D

Formal Name

Direct Low-density lipoprotein cholesterol

This article was last reviewed on

16 May 2022.

This article waslast modified on 16 May 2022.

At a Glance

Why Get Tested?

To help determine your risk of developing heart disease and to monitor lipid-lowering lifestyle changes and drug therapies; to accurately determine your low-density lipoprotein cholesterol (LDL-C) concentration when you have raised triglyceride concentrations

When To Get Tested?

As a follow-up to a lipid profile if your triglycerides are significantly elevated; at regular intervals to monitor efforts to lower LDL concentrations

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

No test preparation is needed. Your doctor might recommend that you fast (water only) for 14 hours prior to the test so that other related substances can be measured in the same sample.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

The direct low-density lipoprotein cholesterol test (direct LDL-C) measures the amount of LDL cholesterol, sometimes called “bad” cholesterol, in the blood. Elevated concentrations are associated with increased risk of atherosclerosis and heart disease. Usually, the amount of LDL cholesterol (LDL-C) is calculated using the results of a standard lipid profile. In most cases, this is a good estimate of the LDL-C, but it becomes less accurate with increased triglyceride concentrations (greater than 4 mmol/L) Direct measurement of LDL-C is less affected by triglycerides and can be used when you are not fasting or when you have significantly elevated triglycerides.

Common Questions

How is it used?

Measurement of low density lipoprotein cholesterol (LDL-C) is helpful in assessing a patient’s risk of heart disease and in monitoring the response to lipid lowering therapy. A standard lipid profile consists of total cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglycerides. By applying a formula, the amount of cholesterol present in low-density lipoprotein can be determined, and this calculated value is typically reported alongside the other values. When triglycerides are high, the formula can no longer be used and the only way to accurately determine LDL-C is to measure it directly.

High triglycerides may be due to a metabolic disorder affecting lipids. However, anyone may have high triglycerides concentrations in their blood after eating. In either situation, the direct LDL-C test can determine the amount of LDL in a patient’s blood.

LDL-C may not be included in all standard lipid profiles, as non-HDL cholesterol is increasingly being used to estimate future cardiovascular risk in many situations rather than LDL-C. Non-HDL cholesterol accounts for other forms of “bad” cholesterol in addition to LDL-C. In some cases both LDL-C and non-HDL cholesterol are reported.
When is it requested?

Direct LDL-C may be requested when calculation of LDL cholesterol will not be accurate because the patient’s triglycerides are significantly elevated.
What does the test result mean?

Elevated concentrations of LDL, as measured with the direct LDL-C test, indicate a greater risk of developing heart disease. Concentrations of LDL-C decrease in response to lipid-lowering lifestyle changes and/or drug therapies indicating a decreased risk of heart disease.

Low concentrations of LDL are not generally a concern and are not monitored. They may be seen in patients with an inherited lipoprotein deficiency and in patients with hyperthyroidism, infection, and inflammation.
Is there anything else I should know?

Direct LDL-C, like calculated LDL-C, should be measured when you are well and “metabolically stable.” Illness, surgery, trauma, a heart attack, sudden weight loss or gain, and pregnancy can all temporarily affect the LDL concentration.
Why hasn't the Direct LDL-C replaced the calculated LDL-C test?

Calculated LDL-C is almost as accurate as direct LDL-C when triglyceride concentrations are normal. It can be done at no additional cost when a standard lipid profile is performed whereas the use of direct testing increases the cost.
Are all LDL molecules the same?

No, LDL and other lipoprotein molecules vary in size and density. Patients with a larger percentage of small dense LDL molecules are believed to be at greater risk for developing atherosclerosis than those with a higher percentage of large LDL. Different sizes of lipoprotein molecules can be separated by density (through ultra-centrifugation), by size and electrical charge (through electrophoresis) and by other techniques. The clinical usefulness of these tests is however, still to be proven.

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Direct LDL Cholesterol